Which of the following cannot act both as a Bronsted acid and as a Bronsted base?

The molar solubility of ${\mathrm{CaF}}_2$ $({\mathrm{K}}_{\mathrm{sp}}=5.3$ $\mathrm{\times }$ ${10}^{-11})$ in 0.1 M solution of NaF will be:

The oxidation state of Cr in ${\mathrm{CrO}}_6$ is:

The number of hydrogen bonded water molecules(s) associated with \(\mathrm{C u S O_{4} . 5 H_{2} O}\) is:

The formula of nickel oxide with metal deficiency defect in its crystal is $N{i}_{0.98}O$. The crystal contains ${\mathrm{Ni}}^{2+}<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{Ni}}^{3+}$ ions. The fraction of nickel existing as $N{i}^{2+}$ ions in the crystal is-

1. 0.96

2. 0.04

3. 0.50

4. 0.31

The correct statement regarding a solution of two components A and B exhibiting positive deviation from ideal behaviour is :

In water-saturated air, the mole fraction of water vapor is 0.02. If the total pressure of the saturated air is 1.2 atm, the partial pressure of dry air is-

1. 1.17 atm

2. 1.76 atm

3. 1.27 atm

4.  0.98 atm

The standard electrode potential (E°) values of  Al³⁺/ Al,  Ag⁺ / Ag, K⁺ / K,  and Cr³⁺ / Cr are –1.66 V, 0.80 V, –2.93 V, & –0.79 V respectively. The correct decreasing order of the reducing power of the metals is:

The density of a 2 M aqueous solution of NaOH is 1.28 g/$c{m}^3$. The molality of the solution is: 
[molecular mass of NaOH = 40 g mol^-1]