Hydrogen gas is generally prepared by the

1

(a)

reaction of granulated zinc with dilute H₂SO₄

(b)

reaction of zinc with conc. H₂SO₄

(c)

reaction of pure zinc with dil. H₂SO₄

(d)

action of steam on red hot coke.

On treatment of hard water with zeolite, sodium ions get exchanged with

1

(a)

Ca²⁺ ions

(b)

Mg²⁺ ions

(c)

H⁺ ions

(d)

OH^-

The higher density of water than that of ice is due to

1

(a)

dipole-dipole interaction

(b)

dipole-induced dipole interaction

(c)

hydrogen bonding

(d)

all of these

Zeolite is

1

(a)

hydrated sodium aluminium silicate - Na₂Al₂Si₂O₈.xH₂O

(b)

hydrated ferric oxide

(c)

sodium hexametaphosphate

(d)

sodium tetraborate

The decomposition of H₂O₂ is retarded by

1

(a)

acetanilide

(b)

glycerol

(c)

sodium bicarbonate

(d)

oxalic acid

Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

1

(a)

Hydrogen atom has only one electron in its 1s-orbital. So, to achieve stable inert gas configuration of helium, it exists as diatomic molecule and is called dihydrogen.

Name the isotope of hydrogen which contains equal number of protons and neutrons.

1

(a)

Deuterium ( \(_{ 1 }^{ 2 }{ H }\))
Number of protons (p) = number of electrons
= atomic number = 1
Number of neutrons (n) = Mass number - atomic number
= 2 - 1 = 1

Which isotope of hydrogen is radioactive?

1

(a)

Tritium \(\left({ }_{1}^{3} \mathrm{H}\right)\) is radioactive because neutron/proton ratio is more than 1.5.

Name the compound each in which hydrogen exists in negative oxidation state

1

(a)

NaH, here oxidation state of hydrogen is -1.

Name the compound each in which hydrogen exists in positive oxidation state

1

(a)

HCl, here oxidation state of hydrogen is +1.

Write the Lewis structure of hydrogen peroxide.

1

(a)

the Lewis structure of hydrogen peroxide is

Which compounds cause temporary hardness of water?

1

(a)

Ca(HCO₃)₂ and Mg (HCO₃)₂

Name a substance which can oxidise H₂O₂.

1

(a)

Acified KMnO₄.

Name the phenomenon of adsorption of hydrogen on metal surface.

1

(a)

Occlusion.

Knowing the properties of H₂O and D₂O, do you think that D₂O can be used for drinking purposes?

2

(a)

Which isotope of hydrogen does not have neutron?

2

(a)

Which type of hydrides are generally non-stoichiometric in nature?

2

(a)

What is the cause of bleaching action of H₂O₂?

2

(a)

What is the use of hydrogen in the manufacture of Vanaspati Ghee?

2

(a)

Calculate the normality of a solution of 1 L of hydrogen peroxide labelled 30 volumes.

3

(a)

Comment on the reactions of dihydrogen with copper(II) oxide

3

(a)

Due to this property hydrogen is used for the manufacture of vanaspati ghee from edible oils such as cotton-seed oil, soyabean oil, corn oil etc.

3

(a)

The aqueous solution of H₂O₂ is acidic in nature. Explain with the help of example. Name two substances which catalyse the decomposition reaction of H₂O₂.

3

(a)

Water molecule is bent, not linear. Explain?

3

(a)

1. At the home of Mr.Kumar, Dalda ghee is generally used. He is suffering from high blood pressure and diabetes. Mr.Sharma, a friend of Mr.Kumar has advised him to change from ghee to vegetable oil like mustard oil.
   Dihydrogen (H₂) is used in the manufacture of vanaspati ghee by hydrogenation of polyunsaturated vegetable oils using nickel as a catalyst.
   Vegetable oil \(\xrightarrow [ { H }_{ 2 } ]{ Ni } \) vanaspati ghee
   Should we use vegetable oils for cooking? why?

   5

   (a)

2. Can we use concentrated sulphuric acid and pure zinc in the preparation of dihydrogen?
   Write the chemical reactions to show the amphoteric nature of water. Why is hydrogen peroxide stored in wax-lined plastic coloured bottles?

   5

   (a)

Complete the following chemical reactions and classify the above into (a) hydrolysis,(b) redox and (c) hydration reactions.
\(MnO_{ 4 }^{ - }(aq)+{ H }_{ 2 }{ O }_{ 2 }(aq)\rightarrow \)

5

(a)