1099+ Important Chemistry MCQ Questions Answers

Q:

How many electrons are there in Na+

A) 1	B) 10
C) 11	D) 12

Answer & Explanation Answer: B) 10

Explanation:

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47 16367

Q:

The electrochemical cell stops working after some time because ________

A) Electrode potential of both the electrodes becomes zero	B) One of electrodes completely vanishes
C) Electrode potential of both electrodes equalizes	D) The reaction reverses its direction

Answer & Explanation Answer: C) Electrode potential of both electrodes equalizes

Explanation:

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92 16220

Q:

Temporary hardness is due to the presence of

A) Calcium carbonate	B) calcium bicarbonate
C) magnesium sulphate	D) calcium sulphate

Answer & Explanation Answer: B) calcium bicarbonate

Explanation:

Temporary hardness is due to the presence of soluble bicarbonates of calcium and magnesium in water. Permanent hardness is due to the presence of sulphates and chlorides of calcium and magnesium.

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41 16209

Q:

The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 $d m^{3}$ at 27°C is to a volume of 100 $d m^{3}$

A) 42.3 J/ mole / K	B) 38.3 J/ mole / K
C) 35.8 J/ mole / K	D) 32.3 J/ mole / K

Answer & Explanation Answer: B) 38.3 J/ mole / K

Explanation:

$∆ s = n R \ln \frac{v 2}{v 1}$

$= 2.303 n R \log \frac{v 2}{v 1}$ = $2.303 \times 2 \times 8.314 \times \log (\frac{100}{10})$ = $38.3 J$ $m o l^{- 1}$ $k^{- 1}$

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43 16204

Q:

Plaster of Paris ______.

I. changes into gypsum on mixing with water

II. is CaSO4.2H2O

III. is used for decoration

A) Only I and II	B) Only I and III
C) Only II and III	D) All I, II and III

Answer & Explanation Answer: B) Only I and III

Explanation:

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Exam Prep: Bank Exams

0 16041

Q:

Which statement(s) is/are CORRECT regarding Dalton’s Atomic theory?

I. All matters are made of very tiny particles.

II. Atoms of different elements have different masses and chemical properties.

III. The relative number of atoms is variable in any compound.

A) Only I and II	B) Only I and III
C) Only II and III	D) All I, II and III

Answer & Explanation Answer: A) Only I and II

Explanation:

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1 16023

Q:

' Misch metal ' is widely used in manufacture of which of the following

A) Material of car brake	B) Smoke detectors
C) Cigarette lighters	D) Emergency lights

Answer & Explanation Answer: C) Cigarette lighters

Explanation:

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49 15962

Q:

Which of the following statements are CORRECT?

I. Oxides of metals are generally basic.

II. Oxides of non-metals are generally acidic.

III. Non-metals are generally electro positive.

A) Only I and II	B) Only I and III
C) Only II and III	D) All I, II and III

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