1.

The radio-isotope used for treatment of thyroid disorders is

• Na-24

• P-32

• Co-60

• I-131

Two glass bulbs A and B are connected by a very small tube having a stop-cock. Bulb A has a volume of 100 cm³ and contained the gas while bulb B was empty. On opening stop-clock, the pressure fell down to 40%. The volume of the bulb B must be

• 75 cm³

• 125 cm³

• 150 cm³

• 250 cm³

20 mL of 0.2 M NaOH is added to 50 mL of 0.2 M acetic acid. The pH of this solution after mixing is (K_a=1.8x 10°)

• 4.5

• 2.3

• 3.8

• 4

A vessel at 1000 K contains CO₂ with a pressure of 0.5 atm. Some of the CO₂ is converted into CO on the addition of graphite. The value of K if the total pressure at equilibrium is 0.8 atm, is

• 1.8 atm

• 3 atm

• 0.3 atm

• 0.18 atm

For the reaction $2\mathrm{A} + \mathrm{B}\rightleftharpoons \mathrm{C}, ∆\mathrm{H} = \mathrm{x}$ cal, which one of the following conditions would favour the yield of C on the basis of Le-Chatelier principle?

• High pressure, high temperature

• Only low temperature

• High pressure, low temperature

• Only low pressure

Heat of formation, $∆{\mathrm{H}}_{\mathrm{f}}^{°}$ of an explosive compound like NCl₃ is

• positive

• Negative

• Zero

• Positive or Negative

For the reaction,

$$\begin{gathered} {\mathrm{C}}_3{\mathrm{H}}_8\left(\mathrm{g}\right) + 5{\mathrm{O}}_2\left(\mathrm{g}\right) \to 3{\mathrm{CO}}_2\left(\mathrm{g}\right) + 4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \mathrm{at} \mathrm{constant} \mathrm{temperature}, \\ ∆\mathrm{H}-∆\mathrm{E} \mathrm{is} \end{gathered}$$

• RT

• -3RT

• 3RT

• -RT

The favourable conditions for a spontaneous reaction are

• $\mathrm{T} ∆\mathrm{S} >∆\mathrm{H}, ∆\mathrm{H}=+\mathrm{ve}, ∆\mathrm{S}= +\mathrm{ve}$

• $\mathrm{T} ∆\mathrm{S} >∆\mathrm{H}, ∆\mathrm{H}=+\mathrm{ve}, ∆\mathrm{S}= -\mathrm{ve}$

• $\mathrm{T} ∆\mathrm{S} =∆\mathrm{H}, ∆\mathrm{H}= -\mathrm{ve}, ∆\mathrm{S}= -\mathrm{ve}$

• $\mathrm{T} ∆\mathrm{S} =∆\mathrm{H}, ∆\mathrm{H}= -\mathrm{ve}, ∆\mathrm{S}= +\mathrm{ve}$

Which of the following is correct comparison of the stability of the molecules?

• $\mathrm{CN} < {\mathrm{O}}_2^{+}$

• CN = N₂

• N₂ < O₂

• ${\mathrm{H}}_2^{+} > {\mathrm{He}}_2^{+}$

CH₃CH₂Br undergoes Wurtz reaction. We may expect some of the following product

A: CH₃CH₂CH₂CH₃

B: ${\mathrm{CH}}_2={\mathrm{CH}}_2$

C: CH₃-CH₃

Select correct product.

• Only A

• A and B

• A, B and C

• A and C