1099+ Important Chemistry MCQ Questions Answers

Q:

Which gas is known as "Fuel of Future" ?

A) Methane	B) Oxygen
C) Neon	D) Hydrogen

Answer & Explanation Answer: D) Hydrogen

Explanation:

Because of its being pollution free and combustion efficient, Hydrogen gas is called fuel of future. Because of its origin in marshy places, Methane is called as 'Marsh Gas'.

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Q:

What is the gram formula mass of ${Li}_{2} {SO}_{4}$ ?

A) 101.2487	B) 109.9446
C) 111.2687	D) 106.5871

Answer & Explanation Answer: B) 109.9446

Explanation:

The term gram formula mass is synonymous with molecular mass. So, to get this, we must add molar mass of all the elements in this compound.

Given compound is Lithium Sulphate - ${Li}_{2} {SO}_{4}$

Elemental calculation ::

Li - Lithium - 6.941 - 2 - 13.88200 %
S - Sulfur - 32.065 - 1 - 32.065 %
O - Oxygen - 15.9994 - 4 - 63.9976 %

Now, total = 12.6264 + 29.1647 + 58.2090 = 109.9446

Hence, the gram formula mass of Li2SO4 = 109.9446.

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Q:

Which of the following is a regenerated fibre?

A) Terylene	B) Rayon
C) Nylon	D) Silk

Answer & Explanation Answer: B) Rayon

Explanation:

Terylene and nylon are synthetic fibres produced by a process of polymerisation. Terylene is a polyester and nylon, a poyamide.

Silk is purely a natural product obtained from silk worms.

Rayon is a man-made material which consists of purified cellulose in the form of long fibres. Cellulose occurs in the cell wall of plants. Rayon fibre is chemically identical to cotton but has a shine like silk. Since it is basically derived from a natural source (cellulose) it is called a regenerated fibre.

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Q:

What does one mole of H2O correspond to

A) 16 gms	B) 18 gms
C) 20 gms	D) 22 gms

Answer & Explanation Answer: B) 18 gms

Explanation:

The molar mass of H2O can be calculated as the following.

M(H2O)= [2 x M(H)] + [M(O)].

And we know that M(H) = 1g/mol, M(O) = 16g/mol.

So, M(H2O)= 2x1 + 16 = 18g/mol,

That means 1 mole of H2O contains 18g.

Hence, one mole of H2O corresponds to 18 grams.

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Q:

Which compound contains both ionic and covalent bonds?

A) NaNO3	B) CaSO4
C) NH4Cl	D) All of the above

Answer & Explanation Answer: D) All of the above

Explanation:

Here all the given compounds have both ionic and covalent bonds.

NaNO3 - In Sodium nitrate, Nitrate is covalently bonded as nitrogen is bonded with 3 oxygen atoms. And this nitrate is ionically bonded with sodium.

CaSO4 - In Calcium sulphate, sulphate is covalently bonded as sulphur is bonded with 4 oxygen atoms. And this sulphate is ionically bonded with calcium.

NH4Cl - In Ammonium chloride, ammonium is covalently bonded as nitrogen is bonded with 4 hydrogen atoms. And this ammonium is ionically bonded with chlorine.

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Q:

The degree of dissociation ( $α$ ) of a weak electrolyte, $A_{x} B_{y}$ is related to van't Hoff factor (i) by the expression:

$1 . α = \frac{x + y + 1}{i - 1}$

$2 . α = \frac{x + y - 1}{i - 1}$

$3 . α = \frac{i - 1}{x + y + 1}$

$4 . α = \frac{i - 1}{x + y - 1}$

A) 1 is correct	B) 2 is correct
C) 3 is correct	D) 4 is correct

Answer & Explanation Answer: D) 4 is correct

Explanation:

Van't Hoff factor (i) = $\frac{O b s e r v e d C o l l i g a t i v e P r o p e r t y}{N o r m a l C o l l i g a t i v e P r o p e r t y}$

$\begin{matrix} A_{x} B_{y} \\ 1 - α \end{matrix} \to \begin{matrix} x A^{+ y} \\ x α \end{matrix} + \begin{matrix} y B^{- x} \\ y α \end{matrix}$

Total Moles = $1 - α + x α + y α$ = $1 - α (x + y - 1)$

$i = \frac{1 + α (x + y - 1)}{1}$

$\Rightarrow α = \frac{i - 1}{x + y - 1}$

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Q:

Modern periodic table is based on atomic number of the elements. The significance of atomic number was proved by the experiment of ________

A) Moseley's work on X-ray spectra	B) Bragg's work on X-ray diffraction
C) Mulliken's oil drop experiment	D) Discovery of X-ray by Roentgen

Answer & Explanation Answer: A) Moseley's work on X-ray spectra

Explanation:

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Q:

The monomer of polythene is

A) ethylene	B) ethyl alcohol
C) vinyl chloride	D) ethanol

Answer & Explanation Answer: A) ethylene

Explanation:

The monomer of polythene is ethylene.

the_monomer_of_polythene_is1546857163.png image

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