Chemistry Questions and Answers

21.

Among the following the maximum covalent character is shown by the compound

(1)MgCl2

(2)FeCl2

(3)SnCl2

(4) AlCl3

   A.) Option 1
   B.) Option 2
   C.) Option 3
   D.) Option 4

Answer: Option 'D'

According to Fajans rule, cation with greater charge and smaller size favours covalency.

22.

Nucleons are

   A.) protons and neutrons
   B.) neutrons and electros
   C.) protons and electrons
   D.) protons, neutrons and electrons

Answer: Option 'A'

protons and neutrons

23.

What is the systematic name of NH4ClO3?

   A.) Ammonium Chloride
   B.) Ammonium Chlorate
   C.) Ammonium Chlorane
   D.) Ammonium Chlorine

Answer: Option 'B'

In common we all call the systematic name of NH4ClO3NH4ClO3 as Ammonium Chlorate. But originally the systematic name is azanium trioxidochlorate.

24.

Which gas is known as "Fuel of Future"?

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

Answer: Option 'D'

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'.

25.

If people sleep in closed rooms where charcoal fire is burning , they die due to 

   A.) methane
   B.) carbon monoxide
   C.) carbon dioxide
   D.) phosgene

Answer: Option 'B'

A closed room is aplace where charcoal is burnt in limited supply of air. There is every chance for the formation of the deadly poisonous carbon monoxide, which when inhaled, reacts with the iron in haemoglobin of blood and prevents the supply of oxygen. It is said to be treacherous as there can be no previous warning of its presence because it is an odourless and colourless gas.

26.

Chloroform used as anaesthetic should be preserved in the dark in tightly stoppered bottles because otherwise

   A.) it becomes coloured
   B.) it gets evaporated in air
   C.) it gets oxidised to phosgene
   D.) it gets decomposed to chloropicrin

Answer: Option 'C'

Chloroform, CHCl3CHCl3 is easily oxidised to the highly poisonous gas known as phosgene or carbonyl chloride COCl2. Hence if it is used as anaesthetic it should be kept free from sunlight and air.

27.

A mixture of sand and naphthalene can be seperated by __________

   A.) Chromatography
   B.) Sublimation
   C.) Fractional distillation
   D.) Any of them

Answer: Option 'B'

Sublimation

28.

Water always contains hydrogen and oxygen in the ratio 1:8 by weight.This is in accordance with the 

   A.) Law of Conservation of mass
   B.) Law of Multiple Proportions
   C.) Law of Definite Proportion
   D.) Law of Reciprocal Proportions

Answer: Option 'C'

The Law of Definite Proportion states that the same compound, wherever found or however made, always contains the same elements combined together in the same fixede ratio by weight.

29.

Harmful bacteria in drinking water cannot be destroyed by 

   A.) Chlorination
   B.) boiling
   C.) adding caustic soda
   D.) ozonisation

Answer: Option 'C'

Water containing caustic soda cannot be used for drinking

30.

The oldest known organic compound is

   A.) Acetic acid
   B.) Benzene
   C.) Methane
   D.) Urea

Answer: Option 'A'

In the form of vinegar, acetic acid is known from very early times. It is got by oxidation of fermented liquors (10-15%, alcohol) by air under the influence of a bacteria called 'mycoderma acetic'

31.

The process that takes place in the atom bomb is

   A.) radioactive disintegration
   B.) nuclear fission
   C.) chemical decomposition
   D.) nuclear fusion

Answer: Option 'B'

nuclear fission

32.

Cobalt - 60 is commonly used in radiation therapy because it emits

   A.) alpha - rays
   B.) X - rays
   C.) beta rays
   D.) gamma rays

Answer: Option 'D'

gamma rays

33.

Which is the Lightest of all the metals?

   A.) Hydrogen
   B.) Lithium
   C.) Sodium
   D.) Pottasium

Answer: Option 'B'

Lithium is the lightest of all the metals due to its low atomic number among meetals

34.

Which of the following are chemical changes?
A) Cooking of Food
B) Digestion of Food
C) Freezing of water
D) Water is heated up

   A.) A & B
   B.) A, B & C
   C.) C & D
   D.) All the above

Answer: Option 'A'

A) Cooking of Food  ------ Chemical Change

B) Digestion of Food ----- Chemical Change

C) Freezing of water ----- Physical Change

D) Water is heated up ---- Physical Change

because here the chemical composition of the substance changes in A & B only.

Since we know that, If the chemical composition is changing then it is a chemical change and if the chemical composition is remaining the same, then it is a physical change.

35.

PAS is a drug used in the treatment of

   A.) Malaria
   B.) Tuberculosis
   C.) Cancer
   D.) Typhoid

Answer: Option 'B'

Para-amino salicylic acid (PAS) is used in the treatment of Tuberculosis.

36.

Which of the following is not a pure substance?

   A.) Water
   B.) Oxygen
   C.) Carbon dioxide
   D.) Milk

Answer: Option 'D'

Milk

37.

The oldest known organic compound is

   A.) Acetic acid
   B.) Urea
   C.) Methane
   D.) Benzene

Answer: Option 'A'

In the form of vinegar, acetic acid is known from very early times. It is got by oxidation of fermented liquors (10-15%, alcohol) by air under the influence of a bacteria called 'mycoderma acetic'

38.

Of the following elements, which one has the same oxidation  state in all of its compounds?

   A.) Carbon
   B.) oxygen
   C.) Fluroine
   D.) Hydrogen

Answer: Option 'C'

Fluroine

39.

Which of the following chemical compounds has the highest boiling point?

   A.) Dimethyl ether (CH3OCH3)
   B.) Methanol (CH3OH)
   C.) Methane (CH4)
   D.) None of these

Answer: Option 'B'

Chemical Compounds with stronger intermolecular forces have higher boiling points.
The order of strengths of intermolecular forces is:
 London dispersion < dipole-dipole < H-bonding
Methane (CH4) — London dispersion forces
Dimethyl ether (CH3OCH3) — dipole-dipole attractions
Methanol (CH3OH) — hydrogen bonding
Therefore, Methanol - CH3OH with H-Bonding have highest Boiling Point among the given chemical compounds.

40.

The metal which reacts most violently with with cold water is

   A.) magnesium
   B.) potassium
   C.) calcium
   D.) sodium

Answer: Option 'B'

potassium


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