According to Bohr's theory, which of the following correctly represents the variation of energy and radius of an electron in n^th orbit of H-atom?

• E_n $\propto \frac{1}{{\mathrm{n}}^2}$, r $\propto \frac{1}{{\mathrm{n}}^2}$

• E_n $\propto \frac{1}{{\mathrm{n}}^2}$, r $\propto {\mathrm{n}}^2$

• E_n $\propto$n², r $\propto$n²

• E_n $\propto$n, r $\propto \frac{1}{\mathrm{n}}$

Best reagent for the conversion of AgNO₃ to Ag is

• HClO₄

• H₃PO₂

• HIO₄

• I₂

K_P for the reaction A $\rightleftharpoons$ B is 4. If initially only A is present then what will be the partial pressure of B after equilibrium?

• 1.2

• 0.8

• 0.6

• 1

Which of the following molecules has more than one lone pair ?

• SO₂

• XeF₂

• SiF₄

• CH₄

10 ml of liquid carbon disulphide (specific gravity 2.63) is burnt in oxygen. Find the volume of the resulting gases measured at STP.

• 23.25 L

• 22.26 L

• 23.50 L

• 20.08 L

Which of the following reactions does not take place?

BF₃ + F^- $\to$B${\mathrm{F}}_4^{-}$          ...(I)

BF₃ + 3F^- $\to$B${\mathrm{F}}_6^{3-}$       ...(II)

AlF₃ + 3F^- $\to$ Al${\mathrm{F}}_6^{3-}$    ...(III)

• Only (I)

• Only (II)

• Only (III)

• Only (I) and (III)

An element (X) belongs to fourth period and fifteenth group of the periodic table. Which one of the following is true regarding the outer electronic configuration of (X)? It has

• partially filled d orbitals and completely filled s orbital

• completely filled s orbital and completely filled p orbitals

• completely filled s orbital and half-filled p orbitals

• half-filled d orbitals and completely filled s orbital.

Four diatomic species are listed below in different sequences. Which of these represents the correct order of their increasing bond order?

• ${\mathrm{C}}_2^{2-}$ < ${\mathrm{He}}_2^{+}$ < NO < ${\mathrm{O}}_2^{-}$

• ${\mathrm{He}}_2^{+}$ < ${\mathrm{O}}_2^{-}$ < NO < ${\mathrm{C}}_2^{2-}$

• ${\mathrm{O}}_2^{-}$ < NO < ${\mathrm{C}}_2^{2-}$ < ${\mathrm{He}}_2^{+}$

• NO < ${\mathrm{C}}_2^{2-}$ < ${\mathrm{O}}_2^{-}$ < ${\mathrm{He}}_2^{+}$

The true statement for the acids of phosphorus, H₃PO₂ H₃PO₃ and H₃PO₄ is

• the order of their acidity is H₃PO₄ > H₃PO₃ > H₃PO₂

• all of them are reducing in nature

• all of them are tribasic acids

• the geometry of phosphorus is tetrahedral in all the three.

Assertion : H₃BO₃ is a weak acid.

Reason : Water extracts the proton of H₃BO₃.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false

• If both assertion and reason are false.