Which one of the following order is correct for the first ionisation energies of the elements?

• B <Be <N < O

• Be <B <N < O

• B <Be <O <N

• B <O <Be <N

The cubic unit cell of a metal (molar mass = 63.55 g mol^-1) has an edge length of 362 pm. Its density is 8. 92 g cm^-3. The type of unit cell is

• primitive

• face centred

• body centred

• end centred

The equilibrium constant for the given reaction is 100.

${\mathrm{N}}_2\left(\mathrm{g}\right) + 2{\mathrm{O}}_2\left(\mathrm{g}\right) \rightleftharpoons 2{\mathrm{NO}}_2\left(\mathrm{g}\right)$

What is the equilibrium constant for the reaction given below? 

${\mathrm{NO}}_2\left(\mathrm{g}\right) \rightleftharpoons \frac{1}{2} {\mathrm{N}}_2\left(\mathrm{g}\right) + {\mathrm{O}}_2\left(\mathrm{g}\right)$

• 10

• 1

• 0.1

• 0.01

20 mL of 0.1 M acetic acid is mixed with 50 mL of potassium acetate. K_a of acetic acid = 1.8 x 10^-5 at 27C. Calculate concentration of potassium acetate if pH of the mixture is 4.8.

• 0.1 M

• 0.04 M

• 0.4 M

• 0.02 M

15.

$$\begin{gathered} \mathrm{Calculate} ∆\mathrm{H}° \mathrm{for} \mathrm{the} \mathrm{reaction}, \\ {\mathrm{Na}}_2\mathrm{O}\left(\mathrm{s}\right) + {\mathrm{SO}}_3\left(\mathrm{g}\right) \to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{g}\right) \\ \mathrm{given} \mathrm{the} \mathrm{following}: \\ \left(\mathrm{A}\right) \mathrm{Na}\left(\mathrm{s}\right) +{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \to \mathrm{NaOH}\left(\mathrm{s}\right) + \frac{1}{2}{\mathrm{H}}_2\left(\mathrm{g}\right) ;∆\mathrm{H}°= -146 \mathrm{kJ} \\ \left(\mathrm{B}\right) {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{s}\right) +{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \to 2 \mathrm{NaOH}\left(\mathrm{s}\right) + {\mathrm{SO}}_3\left(\mathrm{g}\right); ∆\mathrm{H}°=+ 418 \mathrm{kJ} \\ \left(\mathrm{C}\right) 2 {\mathrm{Na}}_2\mathrm{O}\left(\mathrm{s}\right) +2 {\mathrm{H}}_2\left(\mathrm{g}\right) \to 4\mathrm{Na}\left(\mathrm{s}\right) + 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right); ∆\mathrm{H}°= +259 \mathrm{kJ} \end{gathered}$$

• +823 kJ

• -581 kJ

• -435 kJ

• +531 kJ

Identify the alkyne in the following sequence of reactions,

$$\begin{gathered} \mathrm{Alkyne} \underset{\mathrm{Lindlar}\text{'}\mathrm{s} \mathrm{catalyst}}{\overset{{\mathrm{H}}_2}{\to }}\mathrm{A} \stackrel{\mathrm{Ozonolysis}}{\to } \mathrm{B} \mathrm{only} \\ \stackrel{\mathrm{Wacker} \mathrm{process}}{\leftarrow }{\mathrm{CH}}_2={\mathrm{CH}}_2 \end{gathered}$$

• ${\mathrm{H}}_3\mathrm{C}-\mathrm{C}\equiv \mathrm{C}-{\mathrm{CH}}_3$

• ${\mathrm{H}}_3\mathrm{C}-{\mathrm{CH}}_2-\mathrm{C}\equiv \mathrm{CH}$

• ${\mathrm{H}}_2\mathrm{C}=\mathrm{CH}-\mathrm{C}\equiv \mathrm{CH}$

• $\mathrm{HC}\equiv \mathrm{C}-{\mathrm{CH}}_2-\mathrm{C}\equiv \mathrm{CH}$

The chemical entities present in thermosphere of the atmosphere are

• ${\mathrm{O}}_2^{+}, {\mathrm{O}}^{+}, {\mathrm{NO}}^{+}$

• O₃

• ${\mathrm{N}}_2, {\mathrm{O}}_2, {\mathrm{CO}}_2, {\mathrm{H}}_2\mathrm{O}$

• ${\mathrm{O}}_3, {\mathrm{O}}_2^{+}, {\mathrm{O}}_2$

Match the following.

• (A)   (B)   (C)   (D)

  IV     V      II      I

• (A)   (B)   (C)   (D)

  IV      V      I      II

• (A)   (B)   (C)   (D)

  IV      I     III     II

• (A)   (B)   (C)   (D)

  II      V     IV      I

The concentration of an organic compound in chloroform is 6.15 g per 100 mL of solution. A portion of this solution in a 5 cm polarimeter tube causes an observed rotation of -1.2°. What is the specific rotation of the compound?

• +12$°$

• -3.9$°$

• -39$°$

• +61.5$°$

Fluorine reacts with dilute NaOH and forms a gaseous. product A. The bond angle in the molecule of A is

• 104°40'

• 103°

• 107°

• 109°28'