MCQ Questions

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.

Answer: (b) DiOxygen
Explanation:
When sodium peroxide dissolves in water:
2Na₂O₂ + 2H₂O → 4NaOH + O₂

Answer: (c) Neutrons
Explanation:
Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

Answer: (c) Ni
Explanation:
Steam reforming of natural gas is the most common method of producing commercial bulk hydrogen at about 95% of the world production of 500 billion m3 in 1998, or 70 million tonnes by 2018.Hydrogen is used in the industrial synthesis of ammonia and other chemicals. At high temperatures (700 – 1100°C) and in the presence of a metal-based catalyst (nickel), steam reacts with methane to yield carbon monoxide and hydrogen.
CH₄ + H₂O ⇌ CO + 3 H₂

Answer: (c) Hydrogen
Explanation:
Henry Cavendish FRS was an English natural philosopher, scientist, and an important experimental and theoretical chemist and physicist. He is noted for his discovery of hydrogen, which he termed “inflammable air”. He described the density of inflammable air, which formed water on combustion, in a 1766 paper, On Factitious Airs. Antoine Lavoisier later reproduced Cavendishs experiment and gave the element its name.

Answer: (b) Zn
Explanation:
When a base reacts with a metal salt in hydrogen gas is formed. In this reaction metal is zinc & base is Sodium hydroxide. When sodium hydroxide solution is heated with zinc granules then Sodium zincate and hydrogen gas are formed.
2NaOH (aq) + Zn(s) → Na₂ZnO₂ (aq)+ H₂(g)
The salt formed by the reaction between a base and a metal, the metal is present as a part of the Negative ion. In the sodium zincate salt (Na₂ZnO₂) formed by the reaction between Sodium Hydroxide and Zinc metal, the zinc metal is present at a part of a negative ions , zincate ion (ZnO₂^-2 ) All the metals do not react with bases to form salt and hydrogen gas. The main product formed in this reaction is sodium zincate (Na₂ZnO₂)

Answer: (a) Nascent Molecular Hydrogen
Explanation:
The hydrogen set free at the time of its preparation from its compounds is also in atom from and is commonly known nascent hydrogen. The newly born hydrogen is in atomic form that is why it is called nascent hydrogen.

Answer: (b) Pt
Explanation:
Glycerol, phosphoric acid or acetanilide is added to H₂O₂ to check its decomposition.

Answer: (a) 0 to 4 °C
Explanation:
Water show a wide range of anomalies compared to similar liquids or hydrides of other group 16 elements. One of the most talked-about anomalies is the formation of ice from liquid water and how the density changes when we cool the water.

O is a small atom and highly electronegative compared to Hydrogen. So O attracts the covalent clouds of O-H towards itself, thus making water a polar molecule. The hydrogen bonding in water molecules causes high boiling point and liquid state compared to other hydrides of group 16.

When we cool water from higher temperature, the density steadily decreases. At 4 degree C it is the highest. But below 4 degree C, The H-bonds break between the molecules and the molecules get drifted further apart, the volume increases and density decreases. The crystalline form of water is ice. At atmospheric pressure ice crystallises in the hexagonal form, but at very low temperatures it condenses to cubic form leaving gap between the structures, thus increasing the volume again.

Density of ice is less than that of water. Therefore, an ice cube floats on water. In winter season ice formed on the surface of a lake provides thermal insulation which ensures the survival of the aquatic life.

Answer: (b) Copper and HCl(aq)
Explanation:
Copper is a noble metal. As it lies below hydrogen in the electrochemical series. Therefore it cant displace hydrogen from dilute HCl. While iron and sodium lie above hydrogen in the electrochemical series. so they can liberate H₂ either from steam or H₂SO₄ solution.
Fe + H2SO₄ ↔ FeSO₄ + H₂
3Fe + 4H₂O (steam) ↔ Fe₃O₄ + 4H₂
Cu + HCl(g) → No reaction
2Na + 2C₂H₅OH → 2C₂H₅ONa + H₂

Answer: (a) Beta-Emitting
Explanation:
Tritium is a beta-emitting radioactive isotope of hydrogen. Its nucleus consists of one proton and two neutrons, making it three times as heavy as a hydrogen nucleus (with its one proton) and one-and-a-half times as heavy as deuterium (which contains one proton and only one neutron).

Answer: (a) 1.0 g / cm³
Explanation:
Water never has an absolute density because its density varies with temperature. Water has its maximum density of 1 g/cm³ at 4 degrees Celsius. When the temperature changes from either greater or less than 4 degrees, the density will become less then 1 g/cm³. Water has the maximum density of 1 g/cm³ only when it is pure water. Other factors affect waters density such as whether it is tap or fresh water or salt water. These variations of water changes its density because whats in the water has its own density.

Answer: (a) CO
Explanation:
Water gas is a combustion fuel containing carbon monoxide (CO) and hydrogen gas (H₂). Water gas is made by passing steam over heated hydrocarbons.

Answer: (b) 224 ml
Explanation:
2H₂O₂ → 2H₂O + O₂
2 × 34 g = 22400 ml
As 2 × 34 g = 68 g of H₂O₂ liberates
22400 ml O₂ at STP
Therefore, 0.68 g of H₂O₂ liberates
= (0.68 × 22400)/(68) = 224 ml

Answer: (d) All of the above
Explanation:
H₂O₂ show all these properties

Answer: (c) Black Suspension of Lead Sulphide(PbS)
Explanation:
Lead sulphide (black suspension) on reaction with hydrogen peroxide forms lead sulphate and water. Lead sulphate as well as water are colourless, therefore lead sulphite decolourises on addition of hydrogen peroxide.
PbS(s) + 4H₂O₂ (aq) → PbSO₄ (s) + 4H₂O (aq)

Answer: (a) 1
Explanation:
The maximum number of electrons present in a shell is given by the formula 2n², where “n” is the orbit number or energy level index, 1, 2, 3 , …… Hence the maximum number of electrons in different shells are as follows:
First orbit or K-shell will be = 2 × 12 = 2
Hydrogen (H), lithium (Li), and sodium (Na), all have one electron in their outermost shells. This means that they can achieve a stable configuration and a filled outer shell by donating or losing an electron.

Answer: (c) Blue
Explanation:
This is due to the formation of CrO5
K₂Cr₂O₇ + H₂SO₄ + 4H₂O₂ → K₂SO₄ + 2CrO₅ + 5H₂O
So it is Blue

Answer: (b) Multiple
Explanation:
In a sample of hydrogen gas, the number of hydrogen molecules is present. These molecules dissociate and produce hydrogen atoms when heated. Each hydrogen atom contains one electron. The hydrogen atoms absorb different amounts of energy and go to different excited states. From there, they take different paths and come back to ground state. Since different paths are associated with different energies, different spectral lines are formed in the spectrum.

Answer: (b) 90%
Explanation:
H₂O₂ is used as an oxidant for rocket fuel. Usually, 90% concentration of H₂O₂ is used.

Answer: (c) 4
Explanation:
Hydrogen has three main isotopes; Protium (¹H), deuterium (²H) and tritium (³H). These isotopes form naturally in nature. Protium and deuterium are stable. Tritium is radioactive and has a half-life of about 12 years. Scientists have created four other hydrogen isotopes (4H to 7H), but these isotopes are very unstable and do not exist naturally.
The main isotopes of hydrogen are unique because they are the only isotopes that have a name.

Answer: (b) Microeconomics

Answer: (a) Macroeconomics

Answer: (b) The General Theory of Employment, Interest, and Money

Answer: (c) 1936

Answer: (a) 1929-30

Answer: (b) J. M. Keynes

Answer: (d) Macroeconomics

Answer: scarcity

Answer: whole

Answer: Adam Smith

Answer: 1936

Answer: investment

Answer: 1929-33

Answer: True

Answer: True

Answer: False

Answer: False

Answer: False

Answer: False

Answer: