Assertion (A): Equal moles of different substances contain same number of constituent particles.

Reason (R) : Equal weights of different substances contain the same number of constituent particles.

The correct answer is

• Both (A) and (R) are true and (R) is the correct explanation of (A)

• Both (A) and (R) are true but (R) is not the correct explanation of (A).

• (A) is true, but (R) is false

• (A) is false but (R) is true

Calculate enthalpy for formation of ethylene from the following data

$$\begin{gathered} \left(\mathrm{I}\right) {\mathrm{C}}_{\left(\mathrm{graphite}\right)} + {\mathrm{O}}_2\left(\mathrm{g}\right) \to {\mathrm{CO}}_2\left(\mathrm{g}\right); ∆\mathrm{H} = 393.5 \mathrm{kJ} \\ \left(\mathrm{II}\right) {\mathrm{H}}_2\left(\mathrm{g}\right) + \frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) \to {\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right); ∆\mathrm{H} = -286.2 \mathrm{kJ} \\ \left(\mathrm{III}\right) {\mathrm{C}}_2{\mathrm{H}}_4\left(\mathrm{g}\right) + 3{\mathrm{O}}_2\left(\mathrm{g}\right) \to 2{\mathrm{CO}}_2\left(\mathrm{g}\right) + 2{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right): ∆\mathrm{H} = -1410.8 \mathrm{kJ} \end{gathered}$$

• 54.1 kJ

• 44.8 kJ

• 51.4 kJ

• 48.4kJ

A radioactive substance ₈₈X²²⁸ (IIA) emit 3α and 3β particles to form "Y". To which group of long form of the periodic table does "Y" belong ?

• IVA

• VA

• VIA

• VIIA

Which of the following is not a conjugate acid-base pair?

• ${\mathrm{HPO}}_3^{2-}, {\mathrm{PO}}_3^{3-}$

• ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}, {\mathrm{HPO}}_4^{2-}$

• ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}, {\mathrm{H}}_3{\mathrm{PO}}_4$

• ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}, {\mathrm{PO}}_3^{3-}$

The wavelength of a spectral line emitted by hydrogen atom in the Lyman series is $\frac{16}{15\mathrm{R}} \mathrm{cm}$. What is the value of n₂? ( R= Rydberg constant).

• 2

• 3

• 4

• 1

The decreasing order of bond dissociation energies of C-C, C-H and H-H bonds is

• H-H > -C-H> -C-C-

• -C-C- > C-H> H-H

• -C-H >-C-> H-H

• C-C- > H-H > -C-H

138 g of ethyl alcohol is mixed with 72 g of water. The ratio of mole fraction of alcohol to water is

• 3 :4

• 1: 2

• 1:4

• 1: 1

Hybridisation of oxygen in diethyl ether is

• sp

• sp²

• sp³

• sp³d

Which one of the following salts give an acidic solution in water?

• CH₃COONa

• NH₄Cl

• NaCl

• CH₃COONH₄

The maximum number of sub-levels, orbitals and electrons in N shell of an atom are respectively

• 4, 12, 32

• 4, 16, 30

• 4, 16, 32

• 4, 32, 64