1. Nature and Composition of Substances

Q- An alloy is
(a) a compound
(b) an allotropic form
(c) an isomer
(d) a mixture
Ans: (d)

Q- Which one is the pure element?
(a) Glass
(b) Cement
(c) Sodium
(d) None of the above
Ans: (c)

Q- Air is
(a) compound (b) element
(c) mixture (d) solution
Ans: (c)

Q- The mass of one atom of hydrogen is approximately
(a) 1 g
(b) 1.5 g
(c) 1.6 × 10-24 g
(d) 3.3 × 10-24 g
Ans: (c)

Q- The isotopes of chlorine with mass number 35 and 37 exist in the ratio of
(a) 1 : 2 (b) 2 : 3
(c) 3 : 1 (d) 3 : 4
Ans: (c)

Q- A gas is found to have the formula (CO)n. Its vapour density is 70. The value of must be
(a) 5
(b) 4
(c) 9
(d) 6
Ans: (a)

Q- In known elements, the maximum number is of
(a) metals
(b) non-metals
(c) metalloids
(d) None of the above
Ans: (a)

Q- Which one of the following laws directly explains the law of conservation of mass?
(a) Hund’s rule
(b) Dalton’s law
(c) Avogadro’s law
(d) Berzelius hypothesis
Ans: (c)

Q- Which one of the following mixture is homogeneous?
(a) Starch and sugar
(b) Methanol and water
(c) Graphite and charcoal
(d) Calcium carbonate and calcium bicarbonate
Ans: (b)

Q- A pure substance can only be
(a) compound
(b) an element
(c) an element or a compound
(d) a heterogeneous mixture
Ans: (c)

Q- The M.K.S. system was first introduced by
(a) Archimedes (b) Einstein
(c) Newton (d) Giorgi
Ans: (d)

Q- The best standard of atomic mass is
(a) carbon-12
(b) oxygen-16
(c) hydrogen-1.008
(d) chlorine-35.5
Ans: (a)

Q- The credit for the discovery of transuranic element goes to
(a) Hahn (b) Rutherford
(c) Seaborg (d) Curie
Ans: (c)

Q- Oxygen and ozone are
(a) allotropes
(b) isomers
(c) isotopes
(d) isobars
Ans: (a)

Q- 1 amu is equal to
(a) 1.00758 g
(b) 0.000549 g
(c) 1.66 × 10-24 g
(d) 6.02 × 10-23 g
Ans: (c)

Q- Which one among the following is the heaviest?
(a) 1 mole of water molecules
(b) 1 mole of ammonia molecules
(c) 1 mole of sodium atoms
(d) 1 mole of hydrogen molecules
Ans: (c)

Q- Which of the following is an element?
(a) Alumina (b) Brass
(c) Graphite (d) Silicon
Ans: (d)

Q- What is the number of P atoms in one mole of P4?
(a) 1.504 × 1023
(b) 6.023 × 1023
(c) 1.209 × 1024
(d) 2.409 × 1024
Ans: (d)

Q- How many moles are there in 140 g of Si (atomic mass of silicon is 28)?
(a) 5 (b) 10
(c) 28 (d) 140
Ans: (a)

Q- How many electrons are there in Na+?
(a) 1 (b) 10
(c) 11 (d) 12
Ans: (b)

Q- Which one of the following substances does not have a melting point?
(a) Bromine (b) Sodium chloride
(c) Mercury (d) Glass
Ans: (d)

Q- A mixture of sand and naphthalene can be separated by
(a) fractional distillation
(b) sublimation
(c) chromatography
(d) Any of them
Ans: (b)

Q- Which of the following is a mixture?
(a) Distilled water
(b) Gasoline
(c) Liquefied petroleum gas
(d) Both (b) and (c)
Ans: (d)

Q- A metal which forms amalgams is
(a) Potassium
(b) Calcium
(c) Mercury
(d) Silicon
Ans: (c)

Q- Which one of the following is not a mixture?
(a) Air (b) Mercury
(c) Milk (d) Cement
Ans: (b)

Q- Which one of the following is not an element?
(a) Diamond (b) Ozone
(c) Silica (d) Graphite
Ans: (c)

Q- The most abundant metal in earth crust is
(a) iron (b) magnesium
(c) calcium (d) aluminium
Ans: (d)

Q- Consider the following statements: Equivalent weight of the compound is the weight of it that combines with or displaces directly
1. 1.008 part by weight of hydrogen.
2. 16 parts by weight of nitrogen.
3. 35.45 part by weight of chlorine. Which of the statements given above are correct?
(a) 1, 2 and 3 (b) 1 and 2
(c) 2 and 3 (d) 1 and 3
Ans: (d)

Q- Consider the following elements:
1. Copper 2. Gold
3. Platinum 4. Silver Which of the above elements exists free in nature?
(a) 1 and 2 (b) 2 and 3
(c) 1, 2 and 4 (d) 3 and 4
Ans: (b)

Q- Which one is the compound in the following?
(a) Mercury (b) Ozone
(c) Air (d) Ammonia
Ans: (d)

Q- Which one of the following laws explain the formation of carbon monoxide and carbon dioxide from carbon and oxygen?
(a) Law of conservation of mass
(b) Law of multiple proportion
(c) Law of reciprocal proportions
(d) Law of definite proportions
Ans: (b)

Q- What are the elements present in urea?
(a) C, H, O (b) C, N, O
(c) C, N, H (d) C, O, N, H
Ans: (d)

Q- Diamond is
(a) an element (b) a compound
(c) a mixture (d) a liquid
Ans: (a)

Q- The father of modern chemistry is
(a) Priestley (b) Lavoisier
(c) Dalton (d) Mendeleev
Ans: (b)

Q- An element X forms an oxide XO3. What is the valency of X?
(a) 1 (b) 2
(c) 3 (d) 6
Ans: (d)

Q- Bar is a unit of
(a) pressure (b) force
(c) energy (d) frequency
Ans: (a)

Q- The total number of electrons present in 18mL of water (density of water is 1g/mL)
(a) 6.02 × 1020 (b) 6.02 × 1023
(c) 6.02 × 1024 (d) 6.02 × 1026
Ans: (c)

Q- Sodium carbonate crystals lose water molecules. This property is called
(a) hygroscopy
(b) deliquescence
(c) efflorescence
(d) None of the above
Ans: (c)

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
Ans: (c)

Q- The substances that are composed of two or more different elements in fixed proportion by mass are called
(a) mixture
(b) compound
(c) element
(d) None of the above
Ans: (b)

Q- The law of constant proportions was enunciated by
(a) Dalton (b) Berthelot
(c) Avogadro (d) Proust
Ans: (d)

Q- Which one is not metal?
(a) Sulphur (b) Sugar
(c) Nitrogen (d) All of these
Ans: (d)

Q- Antimony is
(a) metal
(b) non-metal
(c) metalloid
(d) None of the above
Ans: (c)

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