Which of the following statements about hydrogen is incorrect?

1. Hydrogen never acts as cation in ionic salts
2. Hydronium ion, H₃O⁺ exists freely in solution
3. Dihydrogen does not act as a reducing agent
4. Hydrogen has three isotopes of which protium is the most common

The method used to remove temporary hardness of water is:

1.  Synthetic resins method

2.  Calgon's method

3.  Clark's method

4.  Ion-exchange method

In transforming 0.01 mole of PbS to ${\mathrm{PbSO}}_4$, the volume of 10 volume ${\mathrm{H}}_2{\mathrm{O}}_2$ required will be

1. 11.2 ml

2. 22.4 ml

3. 33.6 ml

4. 44.8 ml

Which one is incorrect statement for ${\mathrm{H}}_2{\mathrm{O}}_2$?

1. It decomposes slowly on exposure to light

2. It has a non-planar structure

3. It is immiscible in water

4. It shows its oxidizing action both in acidic and basic medium

The O - O - H bond angles in solid and gas phase of ${\mathrm{H}}_2{\mathrm{O}}_2$ are

1. 90.2$°$ and 111.5$°$

2. 101.9$°$ and 94.8$°$

3. 90.2$°$ and 94.8$°$

4. 101.9$°$ and 111.5$°$ 

500 ml of a sample of water contains 0.5mg of ${\mathrm{CaCl}}_2 \mathrm{and} 0.5 \mathrm{mg} \mathrm{of} {\mathrm{MgCl}}_2$. The degree of hardness of water is

1. 1.95 ppm

2. 2.25 ppm

3. 2.90 ppm

4. 0.95 ppm

Which of the following is correct?

1. Atomic hydrogen is more reactive than nascent hydrogen.

2. Metal hydride are powerful reducing agents

3. Group l hydride are more reactive than group-ll hydrides

4. All of the above

Which of the following property of hydrogen does not resemble to alkali metals?

1. Unipositive ion

2. Formula of oxides

3. Ionization energy

4. Formula of sulphides

Ionic hydrides on treatment with water evolve

1. $H_2$

2. $H_2{O}_2$

3. $H_{2}O$

4. $O_2$

An element having valence shell electronic configuration $3d^{6}4s^2$ when reacts with hydrogen forms

1. Saline hydrides

2. Electron rich hydrides

3. Interstitial hydrides

4. No hydrides