Option A: The ideal body, which emits and absorbs all frequencies is called a black body

Option B:  As temperature increases, distribution of frequency (and energy) increases.

Option C: As temperature increases, radiation emitted is shifted to a lower wavelength, i.e. higher frequency.

Hence, options A, B, C, are correct.

Electronic configuration of Cr atom (z = 24) = 1s², 2s² 2p⁶, 3s² 3p⁶ 3d⁵, 4s¹

when ℓ = 1, p - subshell,

Numbers of electrons = 12

when ℓ = 2, d - subshell,

Numbers of electrons = 5

The possible quantum numbers for 4f electron are n = 4, ℓ = 3, m = – 3, –2 –1, 0, 1 , 2 , 3 and s =   

Of various possiblities only option (a) is possible.

Radial probability increases as r increase reaches a maximum value when r = a0 (Bohr’s radius) and then falls. When  radial probability is very small.

Thus, (a) and (c) are true.

M.e. of FeSO₄·7H₂O in 25 mL = m.e. of KMnO₄ used = 2 m.e.

M.e. of FeSO₄·7H₂O in 1000 mL = 80 m.e.

Mass of FeSO₄·7H₂O in solution = (80 / 1) × 2787 × (1 / 1000) = 22.24 gm

% of FeSO₄·7H₂O = (22.24 / 25) × 100 = 88.96% ≈ 89%

The correct answer is Option B.

The chemical reaction will be:

NaHCO₃ + CH₃COOH →CH₃COONa + H₂O + CO₂

molar mass:

NaHCO₃ = 84

CH₃COOH=60

CH₃COONa=82

CO₂ =44

84gNaHCO₃ + 60gCH₃COOH → 82gCH₃COONa + 44gCO₂

Moles of NaHCO₃ = 6.3/84= 0.075

Moles of CH₃COOH = 15/60= 0.25

∴ NaHCO₃ is the limited reagent.

Moles of CO₂ formed = 0.075

Weight of CO₂ = 0.075×44 = 3.3g

Let atomic weight of x = Mx

atomic weight of y = M_y

we know,

mole = weight /atomic weight

a/c to question,

mole of xy₂ = 0.1

so,

0.1 = 10g/( M_x +2M_y)

M_x + 2M_y = 100g -------(1)

for x₃y₂ ; mole of x₃y₂ = 0.05

0.05 = 9/( 3M_x + 2M_y )

3M_x + 2M_y = 9/0.05 = 9× 20 = 180 g ---(2)

solve eqns (1) and (2)

2M_x = 80

M_x = 40g/mol

and M_y = 30g/mole

Given weight of N₂ gas = 1.4 g

Molar mass of N₂ gas = 28 g

So, mole = given mass/ molar mass

⇒ mole = 1.4/28 = 1/20 mole

Now, number of molecules = mole × avogadro number

⇒ number of molecules = 1/20 × 6.022 × 10²³

⇒ number of molecules = 3.011 × 10²²

Now, we are asked for number of atoms. In N₂, there are 2 atoms, so to obtain number of atoms we will multiply with 2 in number of molecules.

⇒ number of atoms = 2 × 3.011 × 10²²

⇒ number of atoms = 6.022 × 10²²

Cr₂O₇²⁻ + 8H⁺ + 7H₂O₂ → 2Cr³⁺ + 11H₂O + 5O₂

In equation (i), H₂O₂ is oxidized to O₂, and Cr₂O₇²⁻ is reduced to Cr³⁺. This is the correct balanced equation for the oxidation of H₂O₂.

Equations (ii) and (iii) are not stoichiometrically balanced for the redox process.

The answer (A) is correct.