Author name: Prasanna

Answer: (b) 15, 5 and 3
Explanation:
Atomic number (Z) = 15 = P → [Ne] 3s² 3p³
Phosphorus belongs to 15th group
Number of valence electrons 3s² 3p³ = 5 and valency = 3 in ground state.

Answer: (d) Many metals with catalytic properties
Explanation:
Many metals with catalytic properties because (i) They provide surface area for reaction to occur (ii) They decreases the ionisation energy. (iii) They have vacant d-orbitals.

Answer: (b) Xe
Explanation:
Xe has the highest atomic size and molecular weight. Hence, it has strong Vander Waals forces of attraction. Hence, it has the highest boiling point.

Answer: (d) The ratio of their charge and size (i.e. charge density) is nearly the same
Explanation:
The chemistry of lithium is very similar to that of magnesium even though they are placed in different groups because of diagonal relationship.

Answer: (b) N^3-, F^–, Na⁺
Explanation:
Isoelectronic species are the neutral atoms, cations or anions of different elements which have the same number of electrons but different nuclear charge.
Number of electrons in N^3- = 7 + 3 = 10.
Number of electrons in F^– = 9 + 1 = 10
Number of electrons in Na⁺ = 11 – 1 = 10.

Answer: (d) Fe²⁺
Explanation:
Mg²⁺: 1s² 2s² 2p⁶: no unpaired electron
Ti³⁺: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹: one unpaired electron
V³⁺: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹: two unpaired electrons
Fe²⁺: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶: four unpaired electrons

Answer: (d) Sixth
Explanation:
16-1s²2s²2p⁶3s²3p⁴ there are 6e^– in outer most shell therefore its group is VIth A

Answer: (c) s and p – Block
Explanation:
Elements in which all the inner shells are complete but outer shell is incomplete is known as representative elements i.e. Those elements which have less than 8 electrons in outermost shell are representative.
s and p block elements except inert gas is known as representative elements.

Answer: (c) Elements with atomic no. 17 and 53
Explanation:
Atomic no. 17(Cl) and 53 (I) are present in the same group

Answer: (d) Fluorine.
Explanation:
Fluorine is the most electronegative element. Fluorine has an electronegativity of 3.98 on the Pauling Electronegativity Scale and a valence of 1. A fluorine atom needs one electron to fill its outer electron shell and achieve stability, which is why free fluorine exists as the F^– ion.

Answer: (b) Ar
Explanation:
In the third period of the Periodic Table the element having smallest size is Ar.

Answer: (c) Na
Explanation:
Sodium has 11 electrons which can be written as (2, 8, and 1). Its outer orbit has 1 electron When it is ionized for the first time, the outer most electron is removed very easily, so that it can form the electronic configuration of the nearest inert gas Neon (2, 8).
Neon has 8 electrons in its outermost orbit. Thus it is highly stable. Now, when the second electron is removed, a very very high amount of energy is required because it doesnt want to give away one of its outermost electron by disrupting its stability.
Thus, second ionization energy of sodium is extremely high.

Answer: (b) Metallic Character
Explanation:
The IE, EA increases along the period. The valency initially increases then decreases. The metallic character decreases along the period.

Answer: (a) Bi < P < S < Cl
Explanation:
Increasing order of electronegativity is Bi < P < S < Cl.

Answer: (a) SnO₂
Explanation:
CaO is basic; CO₂ is acidic; SiO₂ is weakly acidic. SnO₂ is amphoteric.

Answer: (d) Stability of +2 oxidation state increase
Explanation:
As we go down the group inertness of ns² pair increase hence tendency to exhibit +2 oxidation state increases and that of +4 oxidation state decreases.

Answer: (d) He, Ne, Ar, Kr
Explanation:
All the noble gases occupy the peaks of I.E. curve.

Answer: (d) atomic numbers
Explanation:
The Periodic Law states that the physical and chemical properties of the elements recur in a systematic and predictable way when the elements are arranged in order of increasing atomic number.

Answer: (b) 15, 5 and 3
Explanation:
Atomic number (Z) =15 =P → [Ne] 3s² 3p³
Phosphorus belongs to 15th group
Number of valence electrons 3s² 3p³ = 5 and valency = 3 in ground state.

Answer: (c) 1s², 2s2p⁶, 3s²
Explanation:
1s², 2s2p⁶, 3s² – In III transition e^– is to be removed from stable configuration.

Answer: (a) 0
Explanation:
BrF₅ has octahedral geometry and square pyramidal shape.
It has one lone pair and five bond pairs. So, geometry will be octahedral. But since lone pair repels too much, all the four bond pairs that had to be on a square planar surface, will tilt. This will result in a destructed geometry.

Answer: (a) sp²
Explanation:
The hybridisation of sulphur in SO₂​ is sp². Sulphur atom has one lone pair of electrons and two bonding domains. Bond angle is <120° and molecular geometry is V-shape, bent or angular

Answer: (b) sp and sp²
Explanation:
Allene: H₂​C = C = CH₂. The central carbon is attached to other carbons by two sigma and two pi bonds so its hybridisation will be sp. The terminal carbon is attached to other carbon and hydrogen by 3 sigma and 2 pi bonds and hence, its hybridisation will be sp²

Answer: (c) sp³, 0
Explanation:
The central atom of POCl₃ that is P has sp3 hybridization and the number of lone pairs over the central atom in POCl₃ is zero.

The central atom is P, which has 5 valence electrons. Out of them, two valence electrons are used to form a P = O double bond, while the other 3 valence electrons are used to form 3 P-Cl bonds. The molecular geometry of POCl₃ is tetrahedral with asymmetric charge distribution around the central atom. Therefore this molecule is polar. The structure of this compound is tetrahedral and hybridisation of P is sp³.

On the central atom P, there are 4 bonding electron clouds (1 P = O double bond and 3 P-Cl bonds) but no lone pair of electrons.

Answer: (d) K⁺ < Ca²⁺ < Mg²⁺ < Be²⁺
Explanation:
High charge and small size of the cations increases polarisation.
As the size of the given cations decreases as
K⁺ > Ca²⁺ > Mg²⁺ > Be²⁺
Hence, polarising power decreases as K⁺ < Ca²⁺ < Mg²⁺ < Be²⁺

Answer: (c) Acetonitrile
Explanation:
Acetonitrile does not contain sp² hybridized carbon.

Answer: (c) O₂^–
Explanation:
O₂^–(17)Super oxide has one unpaired electron. Since Paramagnetism is shown by those molecules which have at least one unpaired electron, hence, O₂^– is paramagnetic.
Option 1)
NO⁺
This solution is incorrect
Option 2)
CO
This solution is incorrect
Option 3)
O₂^–
This solution is correct
Option 4)
CN^–
This solution is incorrect

Answer: (c) Triangular
Explanation:
When three electrons pairs get as far apart from each other, a trigonal planar structure is formed. The bond angle in this structure will be 120°.

Answer: (b) A₂ B₃
Explanation:
A has 3 electrons in outermost orbit and B has 6 electrons in its outermost orbits. So A can give three electrons to complete its octet and B needs 2 electrons to complete its octet. So 2 atoms of A will release 6 electrons and 3 atoms of B will need six electrons to complete their octet
So, the formula will be A₂​B₃

Answer: (b) SF₄
Explanation:
Bond angle is determined by the hybridization.
SO₂ ​ undergo sp3 hybridization and exhibits 109° bond angle
BBr₃​ undergo sp2 hybridization and exhibits 120° bond angle
CS₂​ undergo sp hybridization and exhibits 180° bond angle.
SF₄​ undergo sp3 d hybridization and exhibits different bond angles.
So, the least bond angle is exhibited by CS₂

Answer: (c) NaCl
Explanation:
The highest melting point will be NaCl, it is because, the lattice energy decreases as the size of alkali metal increases so going down the group the melting point decreases, but due to the covalent bonding in LiCl, its melting point is lower than NaCl and so NaCl is expected to have maximum melting point in the alkali chlorides.​

Answer: (d) Ice
Explanation:
Ice is held together by hydrogen bonds.

Answer: (d) NO⁺ and CN⁺
Explanation:
CN⁻ and NO⁺ are isoelectronic 14 and have same bond order.

Answer: (c) HCl and He atoms
Explanation:
HCl is polar (μ ≠ 0) and He is non-polar (μ = 0) gives dipole-induced dipole interaction.

Answer: (b) sp and sp²
Explanation:
Allene: H₂​C = C = CH₂. The central carbon is attached to other carbons by two sigma and two pi bonds so its hybridisation will be sp. The terminal carbon is attached to other carbon and hydrogen by 3 sigma and 2 pi bonds and hence, its hybridisation will be sp²

Answer: (c) Molecular Solids
Explanation:
Molecular solids are the weakest.
Because Ionic solids and metallic solids are a type of bond. Bonds are stronger than Van der Waals forces.

Answer: (b) sp²
Explanation:
sp² hybrid structures have trigonal planar geometry, which is two dimensional.

Answer: (c) 16.66
Explanation:
μ_ionic = (1.6 × 10⁻¹⁹ C)(1.25 × 10⁻¹⁰ m)/(3.335 × 10⁻³⁰) (Cm/D)
= 5.99 D
%ionic character = (100 × μ_obs)/ (μ_ionic)
=100 × 15.99 = 16.66%

Answer: (b) One sigma, two pi
Explanation:
A single bond between two atoms is always considered as sigma bond.
A double bond between two atoms is always considered as one sigma and one pi bond
A triple bond between two atoms is always considered as one sigma bond and two pi bonds.
So according to the given structure CaC₂ (Calcium carbide) has 1 sigma and 2 pi bonds

Answer: (b) BeCl₂
Explanation:
Ionic or electrovalent bonds are called non-directional bonds, the meaning of non-directional is that these type of bonds does not have any special type of geometry, that is only attraction of positive and negative charge as we know ionic bonds made between metal[positively charged] and non-metal[negatively charged]

RbCl is ionic compound and non-directional

Answer: (d) C < B < A
Explanation:
Under similar conditions of temperature and pressure, equal volumes of different gases contain equal number of moles.
Therefore, Masses of O₂, Ne and CH₄ will be in the ratio 32 : 20 : 16
So, increasing order of their mass is oxygen > neon > methane

Answer: (c) High temperature, low pressure
Explanation:
At high temperature and low pressure, the gas volume becomes large and both intermolecular force as well as the molecular volume can be neglected. Under this condition postulate of kinetic theory applies appropriately and gas approaches ideal behavior.

Answer: (b) 2 : 1
Explanation:
For B, P₁ = P, V₁ = V, T₁ = T.
For A, P₁ = 2P, = 2P, V₂ = 2P,T₁ = 2T
Applying ideal gas equation, PV = nRT.
(P₁V₁)/ (n₁RT₁) = (P₂V₂)/ (n₂RT₂)
or (PV)/(n₁RT) = (2p × 2V)/(n₂R(2T))
or (n₂/n₁) = (2/1)

Answer: (c) In a straight line path
Explanation:
ln between two successive collisions, no force is acting on the gas molecules. Resultantly they travel with uniform velocity during this interval and hence, moves along a straight line.

Answer: (b) Polymorphism
Explanation:
Polymorphism, in crystallography, the condition in which a solid chemical compound exists in more than one crystalline form; the forms differ somewhat in physical and, sometimes, chemical properties, although their solutions and vapours are identical.

Answer: (a) Pascal
Explanation:
Pressure is the effect of a force applied to an area of any surface. The basic unit of pressure is obtained from combining base units which are force over area.
Pressure = (Force/Area)
Unit of force is: Newton(N)
Unit of Area is: m²(metre)
P = N/m²
And the unit of pressure in SI system is Pascal which is denoted by Pa.
1 Pa = 1 (N/m²)

Answer: (b) Less
Explanation:
As gas pressure increases mean free path of the gas decreases.
Mean free path is the distance travelled by a gas molecule between two successive collisions.
So, as pressure increases number of collisions also increases. Hence, mean free path decreases.​

Answer: (c) 760 mm
Explanation:
Standard atmosphere, unit of pressure, equal to the mean atmospheric pressure at sea level. It corresponds to the pressure exerted by a vertical column of mercury (as in a barometer) 760 mm (29.9213 inches) high. One standard atmosphere, which is also referred to as one atmosphere, is equivalent to 101,325 pascals, or newtons of force per square metre (approximately 14.7 pounds per square inch).

Answer: (b) Gaseous Diffusion
Explanation:
Graham found experimentally that the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles. This formula can be written as:
(Rate₁/ Rate₂) = (M₂/ M₁)^(1/2)
where:
Rate₁ is the rate of effusion for the first gas. (volume or number of moles per unit time).
Rate₂ is the rate of effusion for the second gas.
M₁ is the molar mass of gas 1
M₂ is the molar mass of gas 2.

Grahams law states that the rate of diffusion or of effusion of a gas is inversely proportional to the square root of its molecular weight. Thus, if the molecular weight of one gas is four times that of another, it would diffuse through a porous plug or escape through a small pinhole in a vessel at half the rate of the other (heavier gases diffuse more slowly). A complete theoretical explanation of Grahams law was provided years later by the kinetic theory of gases. Grahams law provides a basis for separating isotopes by diffusion a method that came to play a crucial role in the development of the atomic bomb

Answer: (b) Capillary Action
Explanation:
Capillarity, rise or depression of a liquid in a small passage such as a tube of small cross-sectional area, like the spaces between the fibres of a towel or the openings in a porous material. Capillarity is not limited to the vertical direction. Water is drawn into the fibres of a towel, no matter how the towel is oriented.

Liquids that rise in small-bore tubes inserted into the liquid are said to wet the tube, whereas liquids that are depressed within thin tubes below the surface of the surrounding liquid do not wet the tube. Water is a liquid that wets glass capillary tubes; mercury is one that does not. When wetting does not occur, capillarity does not occur.

Capillarity is the result of surface, or interfacial, forces. The rise of water in a thin tube inserted in water is caused by forces of attraction between the molecules of water and the glass walls and among the molecules of water themselves. These attractive forces just balance the force of gravity of the column of water that has risen to a characteristic height. The narrower the bore of the capillary tube, the higher the water rises. Mercury, conversely, is depressed to a greater degree, the narrower the bore.

Answer: (b) Grahams Law
Explanation:
Grahams law states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight. In the same conditions of temperature and pressure, the molar mass is proportional to the mass density. Therefore the rate of diffusion of different gases is inversely proportional to the square root of their mass densities.
r α √(1/d)
and r α √ (1/M)

Answer: (c) Conduction
Explanation:
Evaporation is a cooling process because when liquid turns to gas. When a liquid evaporates, its molecules convert from the liquid phase to the vapor phase and escape from the surface. Heat drives this process. In order for the molecule to leave the liquid surface and escape as a vapor, it must take heat energy with it. The heat that it takes with it comes from the surface from which it evaporated. Since the molecule is taking heat with it as its leaving, this has a cooling effect on the surface left behind.

Answer: (a) 2 : 1
Explanation:
According to Grahams law
(r₁/ r₂) = √ (M₂/M₁)
(r_He/r_CH4) = √ (16/4)
= (2/1)

Answer: (d) 15 : 16
Explanation:
Let 30g of both are mixed.
Moles of H₂ = (30/2) =15
Moles of C₂H₆ = (30/30) = 1
Mole fraction of H₂ = (15)/(1 + 15) = (15/16)
Which is also the fraction of total pressure executed by H₂

Answer: (a) 30 L
Explanation:
According to the ideal gas equation, we have
PV = nRT
​PV = (w/M) RT
​V = ​ (w/M) (RT/P)
Given values are:
w = 2.8 g
M = Molar mass of CO = 28 g mol^-1
T = 27°C = (273 + 27) = 300 K
P = 0.821 atm
R = 0.0821 L atm mol^-1 K^-1
Putting the values in the formula we get :
V = (2.8 g /28 g mol^-1) × (0.0821 L atm mol^-1 K^-1) × (300 K)/(0.821 atm)
= 3 L

Answer: (c) In a straight line path
Explanation:
ln between two successive collisions, no force is acting on the gas molecules. Resultantly they travel with uniform velocity during this interval and hence, moves along a straight line.

Answer: (b) 32°F and 76 cm
Explanation:
Standard conditions for temperature and pressure are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data.
Until 1982, STP was defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 1 atm (101.325 kPa).
Since 1982, STP is defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 105 Pa (100 kPa, 1 bar).

Answer: (c) Viscosity
Explanation:
Viscosity is a measure of a fluids resistance to flow. It describes the internal friction of a moving fluid. A fluid with large viscosity resists motion because its molecular makeup gives it a lot of internal friction. A fluid with low viscosity flows easily because its molecular makeup results in very little friction when it is in motion.
Gases also have viscosity, although it is a little harder to notice it in ordinary circumstances.

Answer: (b) Polymorphism
Explanation:
Polymorphism, in crystallography, the condition in which a solid chemical compound exists in more than one crystalline form; the forms differ somewhat in physical and, sometimes, chemical properties, although their solutions and vapours are identical.

Answer: (b) Critical Temperature
Explanation:
The critical temperature of a gas is the temperature below which it can be liquefied by application of pressure.

Answer: (a) 1st law of Thermodynamics
Explanation:
Hesss law is an expression of the principle of conservation of energy, also expressed in the first law of thermodynamics, and the fact that the enthalpy of a chemical process is independent of the path taken from the initial to the final state (i.e. enthalpy is a state function).

Answer: (b) -11.224 kJ
Explanation:
P₁V₁ = RT η
10(V₁) = 5(8.3)(300) 1
V₁ = 150(0.0821)
P₁V₁ = P₂V₂
Therefore, 10(150 x0.0821) = 1 (V2)
Therefore V₂ = 10(150 × 0.0821)
Therefore, -P Therefore V = -(1)(9)(150 × 0.0821) 101.3
= -11224 J = -11.224 KJ

Answer: (d) Third Law
Explanation:
The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero. The entropy of a system at absolute zero is typically zero, and in all cases is determined only by the number of different ground states it has. Specifically, the entropy of a pure crystalline substance (perfect order) at absolute zero temperature is zero. This statement holds true if the perfect crystal has only one state with minimum energy.

Answer: (b) Hydrogen
Explanation:
Gas has the highest entropy.

Answer: (a) -5 J
Explanation:
Work done by the gas is negative
∆ U in cyclic process is zero.
Therefore, w = -5J

Answer: (b) Hydrogen Gas
Explanation:
The measure of randomness of a substance is called entropy. Greater the randomness of molecules of a substance greater is the entropy. Here hydrogen gas has more entropy as it shows more randomness/disorderliness due to less molar mass than all the given substances and also in the gas phase.

Answer: (c) 5P₁V₁
Explanation:
Work done = Area under P-V graph = (1/2) (5P₁) (2V₁) = 5P₁ V₁

Answer: (c) Absolute Entropy
Explanation:
The Third Law of Thermodynamics is concerned with the limiting behavior of systems as the temperature approaches absolute zero. Most thermodynamics calculations use only entropy differences, so the zero point of the entropy scale is often not important. However, the Third Law tells us about the completeness as it describes the condition of zero entropy.

Answer: (c) I, II and III
Explanation:
Water is a good heat sink for all of the reasons listed above. Moreover, its large heat capacity, liquid state and ready availability enable us to easily set up a calorimeter such that ∆T is large enough that it can be easily measured and small enough that phase transition temperatures are not reached.

Answer: (c) Endothermic
Explanation:
If the products have a higher energy level than the reactants then the reaction is endothermic.
In an endothermic reaction, the reaction mixture absorbs heat from the surroundings. Therefore, the products will have a higher energy than the reactants and ΔH will be positive.
In an exothermic reaction, the reaction mixture releases heat to the surroundings. Therefore, the products will have a lower energy than the reactants and ΔH will be negative.

Answer: (c) 350 kJ
Explanation:
∆E = q + w
= (600 – 250)
∆E = 350 J

Answer: (a) HCl and NaOH
Explanation:
Strong acid + Strong base → Most exothermic.

Answer: (d) -50.4 kJ
Explanation:
The change in internal energy is given as: ∆U = q + w. In this reaction, q is -64.7 kJ and w is 14.3 kJ. Therefore the correct answer is -50.4 kJ.

Answer: (b) The change in entropy along with suitable change in enthalpy decides the fate of a reaction
Explanation:
ΔG = ΔH – TΔS
For a reaction to be spontaneous, ΔG should be negative. Therefore, resultant of ΔH and TΔS decide show the reaction will be carried.

Answer: (b) w = -11.488 kJ
Explanation:
w = -2.303 η RT log (V₂/V₁)
= -2.303(8 – 3) (300)(2) log (40/4)
= -114.8 100J

Answer: (c) 27.0 kcal
Explanation:
3H₂O(l) → 3H₂O(g);
Δn = 3,
ΔE = ΔH − ΔnRT
= 30 − 3 × (2/1000) × 500
= 27 kcal

Answer: (b) 1.11 × 10⁴ kcal
Explanation:
n = (Mass)/ (Molecular weight)
= (6.4 × 10³)/ (64)
= 100
For 1 mole of CaC₂
∆ H = ∆H_f (CaC) + H_f (CO) – H_f (CaO)
= -14.2 – 26.4 + 151.6 = 111.1 kcal
For 100 moles, ∆H = 1.11 x 10⁴ Kcal

Answer: (a) Continuously Increasing
Explanation:
Energy always flows downhill, and this causes an increase of entropy. Entropy is the spreading out of energy, and energy tends to spread out as much as possible. The universe will have run down completely, and the entropy of the universe will be as high as it is ever going to get.

Answer: (d) Third Law
Explanation:
The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero. The entropy of a system at absolute zero is typically zero, and in all cases is determined only by the number of different ground states it has. Specifically, the entropy of a pure crystalline substance (perfect order) at absolute zero temperature is zero. This statement holds true if the perfect crystal has only one state with minimum energy.

Answer: (c) 83-85
Explanation:
C–C bond 83–85 kcal/mol
It is the energy required to break the bond .It is defined as the standard enthalpy change when a bond is cleaved by homolysis, with reactants and products of the homolysis reaction at 0 K (absolute zero)

Answer: (b) PF₃
Explanation:
BF₃ → Lewis acid (incomplete octet)
PF₃ → Lewis base (presence of lone pair on p atom)
CF₄ → Complete octet
SiF₄ → Lewis acid (empty d-orbital in Si-atom)

Answer: (a) 4.000
Explanation:
Given H₃O⁺ ion concentration = 1 × 10^-10
pH = −log[H⁺], pH = −log[1 × 10^-10],
pH= + 10log10, pH = 10
We know that, pH + pOH = 14 …….. (i)
Put the value of pH in eq. (i)
10 + pOH = 14
pOH = 4.

Answer: (d) Increases With Time
Explanation:
Reaction quotient, Qc is equal to ratio of concentration of products to concentration of reactants at any instant of time. In the beginning of reaction, the concentration of products is negligible as compared to reactants. Therefore, the value of reaction quotient is very less.

Answer: (a) Not a buffer solution with pH < 7
Explanation:
Buffer can accept and donate protons at the same time and HCl is an acid. So, it has pH < 7
So, this is not a buffer and the solution will be acidic.

Answer: (a) 1
Explanation:
N₂O₄ ↔ 2NO₂
1 0 (1 – x) 2x
So total number of moles at equilibrium (if initially 1 mole of N₂O₄ was taken) = (1 – x) + 2x
= (1 + x)

Answer: (c) 1.0 × 10^-4 M
Explanation:
(MX2) ⇔ M²⁺_s + 2X^–_2s
K_SPM_S2 = 4S³
= 4 × 10^-12
Therefore, S = 10^-4
Therefore [M²⁺] = 1.0 × 10^-4M

Answer: (c) BaCl₂
Explanation:
Equimolar solutions of the given chlorides when prepared in water forms their respective hydroxides.
The pH of salt BaCl₂ = 7, whereas SrCl₂ and CaCl₂ = 7 and MgCl₂ < 7.

Answer: (b) -1 to +7
Explanation:
Various oxidation numbers of Iodine are -1, 0, +1, +3, +5, +7.
So, Iodine shows -1 to +7 oxidation state.

Answer: (c) O^–₂
Explanation:
In O₂^– total electrons are 17 moiecular orbital configuration.
O^–₂ has one unpaired electron.

Answer: (b) 8
Explanation:
k_a k_b = k_w
k_b = 10^-8
k_a × 10^-8 = 10^-14
k_a = 10^-6 = [H⁺]
pH = −log [H⁺]
pH = − log 10^-6
= 6pH + pOH
= 14 pOH
= 14 − 6
= 8

Answer: (d) I^–
Explanation:
According to this theory, an acid is a proton donor and a base is a proton acceptor. Every strong Bronsted acid has a weak conjugate base and every strong base has a weak conjugate acid. The acidity increases in halogen group atoms,
HF < HCl < HBr < HI.
So, HI is highly acidic and their conjugate bases decrease in order F^– > Cl^– > Br^– > I^–.

Answer: (c) Its value may increase or decrease with increase in temperature
Explanation:
Increase in the temperature decreases the value of equilibrium constant because forward reaction is exothermic. When the forward reaction is endothermic increase the temperature increases the value of equilibrium constant. These occurs when chemical equilibrium shifts toward the products or reactants.

Answer: (a) 0.1 M CH₃COOH
Explanation:
Since CH₃COOH does not dissociate completely, its 10^-1 M solution does not have pH = 1

Answer: (c) 14
Explanation:
[H₃O⁺] = (K_w)/ [OH^–]
= (10^-14)/ (1)
pH = 14

Answer: (c) 13.30
Explanation:
pH = 13.30
Barium hydroxide is a strong base for both stages of dissociation:
Ba (OH)₂ (s) → Ba²⁺ + 2OH^–
So the solution will have 0.20 M hydroxide ions. Now use the auto dissociation product for water:
[H⁺][OH^–] = 1.0 × 10^-14M
[OH^–] = 2.0 × 10^-1M
[H⁺] = 5.0 × 10^-14M
And then pH = −log₁₀ ([H⁺] = 5.0 × 10^-14)
= 13.30.

Answer: (c) (√(1.6 × 10^-30)/(27)))^(1/4)

Answer: (c) Ag₂S > CuS > HgS
Explanation:
For CuS & HgS K_sp = S² (where s= solubility) & for Ag₂S ; K_sp = ^4S3 (s= solubility) now put the values of K_sp and check in which case the value of S is highest & lowest.
Solubility of CuS : (10^-31)^(1/2) = ( 10^(-31/2));
Ag₂S: (10^-44)^(1/3) =( 10^(-44/3));
HgS;
(10^-54)^(1/2) = (10^-54/2) = (10^-27);
The order of solubility will be as per above values:
Hence , the order of solubility is: Ag₂S > CuS > HgS

Answer: (c) These give unionised acid or base on reaction with added acid or alkali
Explanation:
Consider a buffer of CH₃COOH + CH₃COONa
Addition of acid: H⁺ + CH₃COO – → CH₃COOH
Weak acid
Addition of alkali:
OH^– + CH₃COOH → H₂O + CH₃COO^–
Weak electrolyte
Thus, the addition of acid or alkali does not cause any change in pH.

Answer: (d) There was no reaction.
Explanation:
Mg > Al > Zn > Cu > Ag Copper rod is used to stir solution of Al(NO₃)₃ so no reaction as one above in series will displace metal lower in series.

Answer: (a) 0.11

Answer: (d) 50 mL of 0.1 MC₂H₂O₄
Explanation:
2MnO₄^– + 5C₂O₄^2- + 16H+ → 2Mn²⁺ + 10CO₂ + 8H₂O
Therefore, 2 moles of MNO₄^– equivalent to 5 moles of C₂O₄^2-
20 mL of 0.1 M KMnO₄ = 2 moles of KMnO₄
Also, 50 mL of 0.1 M C₂H₂O₄ equivalent to 5 mol of C₂O₄^2-
Therefore, these are equivalent.

Answer: (d) 2Zn + 2AgCN → 2Ag + Zn(CN)₂
Explanation:
In all the three reaction there is no change in the oxidation states. These are simple ionic reactions.
But in 2Zn + 2AgCN → 2Ag + Zn(CN)₂ there is a change in oxidation state. Ag gains electrons and Zn lose electrons therefore it is a redox reaction.

Answer: (d) O > M > N
Explanation:
Given Reduction Potential:
M → +2.46V
N → +1.13V
O → −3.13V
We know that the electrode which has more reduction potential is a good oxidizing agent and has least reducing power.
While the electrode which has less reduction potential, it has more reducing power.
Therefore, Order of reducing power is: – O > M > N

Answer: (a) Formation of slaked lime from quick lime
Explanation:
Here, in this reaction
CaO + H₂​O → Ca(OH)₂​
Oxidation number doesnt change so its not a redox reaction.

Answer: (b) Two
Explanation:
In alkaline medium the reduction of KMnO₄ with KI will takes place as
2 KMnO₄ + H₂O → 2 KOH + 2 MnO₂
KI + 3[O] → KIO₃
Hence the overall reaction is
KI + 2KMnO₄ + H₂O → KIO₃ + 2 KOH + 2 MnO₂
So, one mole of KI will reduced two moles of KMnO₄

Answer: (b) Formation of H₂O₂ by the oxidation of H₂O.
Explanation:
Autoxidation is any oxidation that occurs in presence of oxygen. The term is usually used to describe the degradation of organic compounds in air (as a source of oxygen). Autoxidation produces hydroperoxides and cyclic organic peroxides. These species can react further to form many products. The process is relevant to many phenomena including aging, paint, and spoilage of foods, degradation of petrochemicals, and the industrial production of chemicals. Autoxidation is important because it is a useful reaction for converting compounds to oxygenated derivatives, and also because it occurs in situations where it is not desired (as in the destructive cracking of the rubber in automobile tires or in rancidification). Water automatically gets oxidised to hydrogen peroxide.

Answer: (d) The oxidation state of sulphur is never less than +4 in its compounds.
Explanation:
Oxidation state of oxygen family
Oxygen shows -2, +2 and -1
Oxidation states other elements show +2, +4 and +6 oxidation states
In H₂S, the oxidation state of S is -2. Oxidation state of S lie between -2 to +6.
Option 1)
S₂ molecule is paramagnetic.
This option is incorrect.
Option 2)
The vapour at 200° C consists mostly of S₈ rings.
This option is incorrect.
Option 3)
At 600° C the gas mainly consists of S₂ molecules.
This option is incorrect.
Option 4)
The oxidation state of sulphur is never less than +4 in its compounds.
This option is correct.

Answer: (d) 10
Explanation:
Oxidation state of Ba in general = +2 and of O = −2
Applying formula, Sum of total oxidation state of all atoms = Overall charge on the compound.
Let oxidation state of Xe in BaXeO₆ be x.
2 + x + 6(−2) = 0,
x = 10
But oxidation state 10 is not possible for Xe. In this case the oxidation state of Xe is equal to maximum possible oxidation state for Xe = +8.

Answer: (b) +6
Explanation:
From the above structure we can observe that 4 oxygen atoms are linked by peroxide linkage. So there oxidation state is -1 as in peroxide.
One oxygen atom is attached normally so its oxidation state is -2. So oxidation state of Cr is x + 4(−1) + (−2) = 0, x = +6

Answer: (b) It is almost unionised
Explanation:
Distilled water is a poor conductor of electricity because it does not contain any dissolved salts in it which can provide it ions to conduct electricity. Impurities in water get ionised to conduct electricity. Hence pure water cannot conduct electricity.

Answer: (a) Increase in oxidation number
Explanation:
Oxidation process Involves:-
Addition of O₂ or electronegative element
Removal of H/ electropositive element
Loss of electrons
Increase in oxidation number

Answer: (d) Rb⁺
Explanation:
The smaller is the ion, the more is hydration, the larger is size, lesser is the mobility.

Answer: (b) It is almost unionised
Explanation:
Distilled water is a poor conductor of electricity because it does not contain any dissolved salts in it which can provide it ions to conduct electricity.
Impurities in water get ionised to conduct electricity. Hence pure water cannot conduct electricity.

Answer: (c) 2
Explanation:
The oxidation number of Fe in K₄ Fe (CN)₆ can be calculated as follows,
Oxidation state of K = 1, CN = -1.
Let Oxidation state of Fe be x. so
4(+1) + x + 6(-1) = 0
Hence x = +2

Answer: (b) This electrode potential is assumed to be zero
Explanation:
The electrode potential of a standard hydrogen electrode is arbitrarily assumed to be zero.

Answer: (d) Decomposition.
Explanation:
Lime water formula is Calcium hydroxide (Ca(OH)₂)
Ca(OH)₂ in the presence of excess heat gives calcium oxide(CaO) , Carbon dioxide (CO₂), and water(H₂O).
In this process excess of heat is given and lime water breaks down in different compounds, therefore it undergoes Thermal decomposition reaction.

Answer: (d) Oxidation of Cu atoms.
Explanation:
When copper turnings are added to silver nitrate solution, the solution becomes brown in color after sometime because copper is more reactive than silver so it displaces silver from silver nitrate solution and form copper nitrate solution.

Answer: (a) 0
Explanation:
The oxidation state of carbon in dichloromethane as x.
Also the charges on H and Cl are +1 and −1 respectively.
Therefore, CH₂​Cl₂ ​→ x + 2(+1) +2(−1) = 0
⇒ x = 0

Answer: (b) +3
Explanation:
Let oxidation state of iodine be x.
x − 3 = 0, x = +3,
Because PO₄^3- has combined oxidation number −3.
Therefore, x − 3 = 0
∴ x = +3
Thus oxidation state of iodine is +3.

Answer: (c) Nernst Equation
Explanation:
The relationship between electrode potentials and concentrations of the substances involved in half cell reaction is given by Nernst Equation.
E = E°−(2.303RT)/(nF) log[Mⁿ⁺]/[M]
Where
E = cell potential (V) under specific conditions
E°= cell potential at standard-state conditions
R = ideal gas constant = 8.314 J/mol^-k
T = temperature (kelvin), which is generally 25C (298 K)
n = number of moles of electrons transferred in the balanced equation
F = Faradays constant, the charge on a mole of electrons = 95,484.56 C/mol
[M] and [Mⁿ⁺] are molar concentrations of element and its cation resp.