Author name: Prasanna

Answer: (d) 4 : 3

Answer: (c) Black rough surface

Answer: (b) 4 : 1

Answer: (d) 16

Answer: (b) t1 < t2 < t3

Answer: (c) Plate

Answer: (d) T² = 2 T¹

Answer: (b) W/ m² K²

Answer: (c) Good-emitter

Answer: (d) (500)4

Answer: (a) Zero

Answer: (c) Forced convection losses

Answer: (a) Circular plate

Answer: (c) Plate

Answer: (b) Highly polished mirror surfaces are very good radiators

Answer: (c) Radiation

Answer: (c) Black rough surface

Answer: (c) 42.85°C

Answer: (c) 4p

Answer: (b) Convection

Answer: (a) H²

Answer: (a) Latent heat of fusion

Answer: (a) nrms << ne

Answer: (a) 727 m/s

Answer: (d) 200 m/s

Answer: (b) Doubled

Answer: (c) The r.m.s. velocity of all the gas molecules is more then the escape velocity of the moons surface

Answer: (c) Latent heat of fusion

Answer: (d) 124 J

Answer: (b) 400 K

Answer: (b) 124 J

Answer: (a) 7.22 J

Answer: (d) Infinite

Answer: (b) Temperature of gas

Answer: (b) J/kg°c

Answer: (b) Double the value at 200 K

Answer: (c) 3 moles of gas

Answer: (c) 15 10-20 J

Answer: (b) Collision frequency will be increases

Answer: (c) Hydrogen

Answer: (b) 0.16 m/s

Answer: (c) 2n

Answer: (c) 2 cm

Answer: (c) 2 sec

Answer: (d) Zero

Answer: (b) 3 k/2

Answer: (a) Kinetic energy increases, potential increases decreases

Answer: (a) parabolic

Answer: (c) 1.44 m

Answer: (b) Increase

Answer: (b) Decrease

Answer: (c) amplitude tends to infinity at resonance

Answer: (a) parabolic

Answer: (a) Greater than T.

Answer: (b) 0.16 m/s

Answer: (b) 1/∏

Answer: (c) remains the same

Answer: (c) -mg sinθ

Answer: (c) A body in S.H.M. its acceleration more at extreme position its directions away from mean position

Answer: (d) 19 : 9

Answer: (c) a sin (wt – kx)

Answer: (d) Stationary wave

Answer: (b) Energy is minimum at nodes and maximum at antinodes

Answer: (b) 0.5 sec

Answer: (c) y = ym log (x – nt)

Answer: (b) 3.3 kilo cycles per second

Answer: (c) 20%

Answer: (b) Parallel to propagation

Answer: (d) Both (b) and (c)

Answer: (c) 260, 250

Answer: (a) 25 kg

Answer: (c) 1 : 2 : 3 : 4

Answer: (d) 196 Hz

Answer: (c) 480 Hz

Answer: (d) Metal

Answer: (b) Density and elasticity of ga

Answer: (b) 2 beats per second with intensity ratio (49/1) between maxima and minima

Answer: (b) Energy is minimum at nodes and maximum at antinodes

Answer: (c) 11 : 12

Answer: (b) 2 cm

Answer: (c) Fe₂ (So₄)₃
Explanation:
Iron (III) sulfate (or ferric sulfate), is the chemical compound with the formula Fe₂(SO₄)₃. Usually yellow, it is a salt and soluble in water.

Answer: (a) 26.89
Explanation:
Atomic weight = (Equivalent weight × Valency)
= (8.9 × 3) = 26.7
(Valency = (26.89)/(8.9) ≈ 3).

Answer: (b) 21
Explanation:
21 atoms are present in the compound CuSO₄. 5H₂O.

Answer: (a) 10
Explanation:
(1/2)th if mass of carbon atom weighs exact as 1 gm as from (1 × 12)/ (12) = 1 amu.
Therefore 10 times of this would be = (10 × 1) = 10 gms.
Hence 10 g would be the molar mass of that atom.

Answer: (a) 81.398 g
Explanation:
Pure ethyl alcohol
= (81.4 – 0.002)
=81.398.

Answer: (d) I₂
Explanation:
Sublimation is going directly from the solid to vapor state without passing through the liquid state. The classic demonstration of sublimation is iodine crystals. Heat them at one end of a sealed tube with the other end cooled. We get a beautiful violet vapor and can watch the iodine crystals form from the vapor in the cool end. Let us Wait for some time and all the solid iodine will disappear in the hot end and reappear as beautiful black crystals in the cold end.

Answer: (b) 4 g atom of Hydrogen
Explanation:
1 mole of CH₄ contains 4 mole of hydrogen atom i.e. 4g atom of hydrogen.

Answer: (d) 10^-21
Explanation:
1 zepto =10^-21

Answer: (a) 24 g of C (12)
Explanation:
Number of atoms = (number of moles × Avogadros number (N A) )
⇒ Number of atoms in 24 g C
= (24/12) × N A= 2N A
Number of atoms in 56 g of Fe
= (56/56) N A = N A Number of atoms in 27 g of A1
= (27/27) N A = N A Number of atoms in 108 g of Ag
= (108/108)N A = N A
Hence, 24 g of carbon has the maximum number of atoms.

Answer: (c) Constant Composition
Explanation:
The H : O ratios in water is fixed, irrespective of its source. Hence it is law of constant composition

Answer: (c) 4
Explanation:
Because 100 gm Hb contains = 0.33 gm Fe
Therefore, 67200 gm Hb = (67200 × 0.33)/ (100 gm)
Fe gm atom of Fe = (672 × 0.33)/(56)
= 4.

Answer: (a) Anion
Explanation:
A charged particle, also called an ion, is an atom with a positive or negative charge.
This happens whenever something called an ionic bond forms.
Two particles that have different numbers of electrons (the smallest particle in an atom which is negative) start reacting to each other.
The particle that has the greater amount of electrons takes the other particles electrons.
One becomes positive because it lost an electron, and the other negative because it got another electron.
The two particles become attracted to each other and mix together, making a new kind of particle.

Answer: (b) 8.0 g Methane
Explanation:
6 g carbon
Moles of carbon = (6/12) = 0.5 mol
Number of carbon atoms
= 0.5 × N_A =0.5N_A (N_A is Avogadro number)
6 g ethane (C₂H₆ two atoms of C per mole)
Moles = (6/30) = 0.2 mol
Number of carbon atoms = 0.2 × 2 × N_A = 0.4 N_A
(Number of carbon atoms = moles of compound X number of C atoms per mol × Avogadro number)
8 g methane (CH₄)
Moles = (8/16) = 0.5 mol
Number of carbon atoms = 0.5 × 1 × N_A = 0.5 N_A
21 g propane (C₃H₈)
Moles = (21/44) =0.48 mol
Number of carbon atoms = 0.48 × 3 × N_A = 1.44 N_A
28 g CO
Moles = (28/28) =1 mol
Number of carbon atoms = 1 × 1 × N_A = N_A

Answer: (a) 39.9 g
Explanation:
Molar gas volume at STP is:
1 mole = 22400 cm³ = 22.4 litres
Density = (mass / volume)
Density = 1.78 g/litre
Volume = 22.4 litres
Mass = (volume × density)
(1.78 × 22.4) = 39.872 g

Answer: (d) 0.1
Explanation:
Molarity = (number of moles of solute / volume of solution in litres)
Here number of moles = (given mass of solute / molar mass)
whereas Normality = ( Number of gram equivalent / volume of solution in liter )
where gram equivalent = ( mass of solute / equivalent mass )
Consider an example of H₂SO₄ whose molar mass = 98 g per mole
Consider a Solution containing 0.98 g of sulphuric acid in 100 ml.
Volume = 100 ml = 0.1 l
Then,
Number of moles = (0.98 / 98)
Number of moles = 0.01
Hence molarity = (0.01 / 0.1) = 0.1 M
Hence Molarity = 0.1 M
Now sulphuric acid is dibasic therefore
Its equivalent weight = (98 / 2)
Hence equivalent weight = 49
So the gram equivalent = (0.98 / 49) = 0.02
Now Normality = (0.02 / 0.1)
Hence the Normality is equal to 0.2 N.
Thus for H₂SO₄ (i.e. dibasic) Normality is 0.2 N and molarity is 0.1 M.

Answer: (c) Ion
Explanation:
A charged particle, also called an ion, is an atom with a positive or negative charge.This happens whenever something called an ionic bond forms. Two particles that have different numbers of electrons (the smallest particle in an atom which is negative) start reacting to each other. The particle that has the greater amount of electrons steals the other particles electrons. One becomes positive because it lost an electron, and the other negative because it got another electron. The two particles become attracted to each other and mix together, making a new kind of particle.

Answer: (b) Law of Conservation of Mass
Explanation:
Balanced chemical equation: A chemical equation in which the number of atoms of reactants and the number of atoms of products is equal is called a balanced equation. Every chemical equation should be balanced because:
i) According to the law of conservation of mass, atoms are neither created not destroyed in chemical reactions.
ii) It means the total mass of the products formed in a chemical reaction must be equal to the mass of reactants consumed.

Answer: (c) Constant Composition
Explanation:
The H : O ratios in water is fixed, irrespective of its source. Hence it is law of constant composition

Answer: (b) Molecular
Explanation:
Molecular formulas indicate the simple numbers of each type of atom in a molecule, with no information on structure. For example, the empirical formula for glucose is CH₂O (twice as many hydrogen atoms as carbon and oxygen), while its molecular formula is C₆H₁₂O₆ (12 hydrogen atoms, six carbon and oxygen atoms).

Answer: (d) 26.7
Explanation:
Atomic weight = (Equivalent weight × Valency)
=(8.9 × 3) = 26.7
(Valency = (26.89)/(8.9) ≈ 3).

Answer: (a) Cu⁺², Ti⁺³
Explanation:
₂₉Cu = [Ar] 3d¹⁰ 4s₁
Cu²⁺ = [Ar] 3d⁹ (n = 1)

₂₂Ti = [Ar] 3d² 4s²
Ti³⁺ = [Ar] 3d² (n = 1)

Both of these ions have one unpaired electron, hence these have same paramagnetic moment.

Answer: (b) Half
Explanation:
Let charge of proton be +e, then charge of alpha particle will be + 2e. Similarly let mass of proton be m, then mass of alpha particle will be 4m.
Now, specific charge = (charge) / (mass of the substance.)
For proton, specific charge = (e/m)
For alpha particle, specific charge = (2e)/ (4m)
Therefore there ratio is: (e/m) × (4m)/ (2e) = 2 : 1

Answer: (d) 4 × 10⁴ cm^-1
Explanation:
Frequency ν = 12 × 10¹⁴s^-1 and
velocity of light c = 3 × 10¹⁰ cms^-1.
We know that the wave number ν^– = (v/c)
= (12 × 10¹⁴)/(3 × 10¹⁰)
= 4 × 10⁴ cm^-1

Answer: (d) (d) and (e)
Explanation:
In the absence of magnetic and electric fields, the orbitals defined by magnetic quantum number are degenerate (of same energy). So, energy of the orbital, in the absence of magnetic and electric fields depends on the (n + l) value.
Higher the (n + l) value, larger the energy of the orbital.
Orbitals with same n and n + 1 values are degenerate and have same energy.
In the given combinations, d and e have same n and n + l value and so, have same energy in the absence of magnetic and electric fields.

Answer: (a) Li²⁺
Explanation:
(1/λ) = Z²R_H [(1/n₁²) – (1/n₂²)], n₁ = 1, n₂ = 2
Therefore, (1/ λ) = Z²R_H [(1/1) – (1/4)]
= (3/4) Z²R_H
λ ∝ (1/Z)²
Therefore, Li²⁺ will produce shortest wave length.

Answer: (a) 1.51 eV
Explanation:
En = (13.6)/(n²) eV
or E = (13.6)/(9)eV
= 1.51 eV

Answer: (d) Chadwick
Explanation:
The essential nature of the atomic nucleus was established with the discovery of the neutron by James Chadwick in 1932 and the determination that it was a new elementary particle, distinct from the proton.

Answer: (c) 50
Explanation:
The maximum number of electrons that can occupy a given energy level n is given by
max. no. of electrons = 2n²
So the number of orbitals that are present in an energy level n is given by
of orbitals = n²
Also a given orbital can hold a maximum of 2 electrons, which is why the maximum number of electrons that can be added to a given energy level n is twice the number of orbitals present on said energy level.
According to given,
n = 5, it refers to the fifth energy level, holds
of orbitals = 5²
of orbitals = 25
This means that the maximum number of electrons that can be added to the fifth energy level is
max no. of electrons = 2 × 25
= 50 electrons

Answer: (c) 5s
Explanation:
According to the Aufbaus principle, electron will be first enters in those orbital which have least energy. So decreasing order of energy is 5p > 4d > 5s.

Answer: (a) 1.05 × 10^-34 Jsec
Explanation:
Electron after absorbing 10.2 eV energy goes to its first excited state (n = 2) from ground state (n = 1).
Therefore, Increase in momentum = (h)/(2π)
= (6.6 × 10^-34)/ (6.28)
= 1.05 × 10^-34 Js.

Answer: (d) 9.84 × 10⁵J mol^-1
Explanation:
Energy required when an electron makes transition from n = 1 to n = 2
E₂ = −(1.312 × 10⁶ × (1)²)/(2²)
= −3.28 × 10⁵J mol^-1
E₁ = −1.312 × 10⁶J mol^-1
ΔE = E₂ − E₁
= −3.28 × 10⁵ – (−13.2 × 10⁶)
ΔE = 9.84 × 10⁵J mol^-1

Answer: (b) 7
Explanation:
For n = 4 and l = 3, the orbital is 4f.
Number of values of m= no. of orbitals= (2l + 1) = 7.

Answer: (c) 14
Explanation:
n = 4, so 4th shell and l = 3 so it is f subshell.
Thus n = 4, l = 3 indicates 4f orbitals.
In f subshell there are 7 orbitals and each orbital can accommodate a maximum of 2 electrons. So, maximum no. of electrons in 4f subshell = 7 × 2 = 14.

Answer: (b) n = 2, Be³⁺
Explanation:
r = (r₀) × (n²/Z) Å
whereas,
r₀ = radius of 1st Bohrs orbit of hydrogen atom = 0.529 Å
For r = r₀^–
(n²/Z) = 1
n² = Z (1)
Because for n = 2 , Be⁺³
Z = 4, which satisfies equation (1).
Hence, n = 2,Be⁺³ will have the same radius of 1 st Bohrs orbit of a hydrogen atom.

Answer: (c) Orientation of orbitals
Explanation:
The magnetic quantum number specifies orientation of orbitals.

Answer: (b) 5 → 2
Explanation:
Since the line in hydrogen spectrum lies within visible region that is at red end, therefore it is corresponds to the Balmer series.
The line at the red end suggests that
The first line of Balmer series is n = 3 to n =2
The second line of Balmer series is n = 4 to n = 2
The third line of Balmer series is n = 5 to n = 2

Answer: (b) 15
Explanation:
The configuration of
₂₄Cr is 1s², 2s², 2p⁶, 3s², 3p⁶, 3d⁵, 4s¹
Therefore, total s-orbitals = 4
total p-orbitals = 6
total d-orbitals = 5 and thus
Thus, total orbitals = 4 + 6 + 5 = 15.

Answer: (c) 10 electrons
Explanation:
n = 6, ℓ = 2 means 6d → will have 5 orbitals.
Therefore max 10 electrons can be accommodated as each orbital can have maximum of 2 electrons.

Answer: (c) n = 3, l = 2, m = 1, s = + 1/2
Explanation:
n = 3, l = 0 represents 3s orbital n = 3, l = 1 represents 3p orbital n = 3, l = 2 represents 3d orbital n = 4, l = 0 represents 4s orbital The order of increasing energy of the orbitals is 3s < 3p < 4s < 3d.

Answer: (d) 4 × 10¹
Explanation:
λ = (c/v) = (3 × 10⁸)/(8 × 10¹⁵)
= 3.75 × 10^-8
= 3.75 × 10^-8 × 10⁹ nm
= 4×10¹ nm.