JEE Chemistry Some Basic Concepts Of Chemistry MCQs Set A

Question: A mixture of sand and iodine can be separated by

• a) sublimation
• b) crystallisation
• c) distillation
• d) fractionation

Answer: sublimation

Question: Difference in density is the basis of

• a) gravity separation
• b) molecular sieving
• c) ultrafiltration
• d) molecular attraction

Answer: gravity separation

Question: Which of the following is an example of a heterogeneous substance?

• a) Candle
• b) Table salt
• c) Bottled water
• d) Pieces of copper

Answer: Candle

Question: Which of the following substances cannot be separated in to its constituents by physical methods?

• a) Solid glucose
• b) Salt and sugar
• c) Sugar and water solution
• d) None of these

Answer: Solid glucose

Question: Which of the following pair of substances contain element and compound within a pair ?

• a) A, C, D
• b) B only
• c) All of these
• d) C and D

Answer: A, C, D

Question: Which of the following statements about a compound is incorrect?

• a) A compound retains the physical properties of its constituent elements
• b) A compound cannot be separated into its constituent elements by physical methods of separation
• c) A molecule of a compound has atoms of different elements
• d) The ratio of atoms of different elements in a compound is fixed

Answer: A compound retains the physical properties of its constituent elements

Question:  Choose the correct combination

• a)

  

  

• b)

  

  

• c)

  

  

• d) None of these

Answer:

Question: Choose the correct statement

• a) The particles of gases are far apart as compared to solids and liquids and their movement is easy and fast.
• b) The particles of gases moves faster than liquids only when the gases are heated.
• c) The particles of solids are arranged in orderly fashion but they can move as freely as liquids
• d) The particle s in liquids are more closely held than gases but less free to move than solids

Answer: The particles of gases are far apart as compared to solids and liquids and their movement is easy and fast.

Question: A mixture contains two or more substances in ________ which are called its ________.

• a) any ratio, components
• b) fixed ratio, elements
• c) fixed ratio, compounds
• d) any ratio, elements

Answer: any ratio, components

Question: Which one of these is not a pure compound?

• a) Sucrose solution
• b) H₂O₂
• c) O₃
• d) H₂O

Answer: Sucrose solution

Question: One fermi is

• a) 10^–13 cm
• b) 10^–12 cm
• c) 10^–15 cm
• d) 10^–10 cm

Answer: 10^–13 cm

Question: The prefix 10¹⁸ is

• a) exa
• b) giga
• c) kilo
• d) nano

Answer: exa

Question: The prefix zepto stands for (in m)

• a) 10^–21
• b) 10^–12
• c) 10⁹
• d) 10^–15

Answer: 10^–21

Question: The unit J Pa^–1 is equivalent to

• a) m³
• b) dm³
• c) cm³
• d) None of these

Answer: m³

Question: Which has highest weight ?

• a) 1 m³ of water
• b) 10 litre of Hg
• c) A normal adult man
• d) All have same weight

Answer: 1 m³ of water

Question:  Which one of the following set of units represents the smallest and largest amount of energy respectively?

• a)

  

• b) erg and cal
• c) J and erg
• d) cal and eV

Answer:

Question: A measured temperature on Fahrenheit scale is 200 °F. What will this reading be on Celsius scale ?

• a) 93.3 °C
• b) 40° C
• c) 94° C
• d) 30° C

Answer: 93.3 °C

Question: Which of the following is not a SI unit?

• a) litre
• b) candela
• c) metre
• d) mole

Answer:  litre

Question: The prefix 10^–24 is

• a) yocto
• b) yotta
• c) zeta
• d) zepto

Answer: yocto

Question: Many countries use Fahrenheit scale for expressing temperature of atmosphere. If temperature in any such country is measured 41°F then what is its value in celcius scale and would you expect hot or cold atmosphere in that country?

• a) 5°C, cold
• b) 15°C, cold
• c) 25°C, normal
• d) 41°C, hot

Answer: 5°C, cold

Question:   A sample was weighted using two different balances. The results were

(i) 3.929 g (ii) 4.0 g

How would the weight of the sample be reported?

• a) 3.93 g
• b) 3.9 g
• c) 3g
• d) 3.929 g

Answer: 3.93 g

Question:  Two students performed the same experiment separately and each one of them recorded two readings of mass which are given below. Correct reading of mass is 3.0 g. On the basis of given data, mark the correct option out of the following statements.

• a) Results of student A are both precise and accurate
• b) Results of both the students are neither accurate nor precise.
• c) Results of student B are neither precise nor accurate
• d) Results of student B are both precise and accurate

Answer: Results of student A are both precise and accurate

Question: 0.00016 can be written as ...A... in scientific notaiton. Here, A refers to

• a) 1.6 × 10^–4
• b) 2.450 × 10^–8
• c) 24.50 × 10^–9
• d) 24.50 × 10^–7

Answer: 1.6 × 10^–4

Question: results reported by three students X, Y and Z are :

X : 6.18 and 6.28
Y : 6.20 and 6.023
Z : 6.22 and 6.24
Which of the following option is correct :

• a) Both X & Y neither precise nor accurate, Z both precise and accurate.
• b) Both X & Z precise & accurate, Y not precise
• c) X precise and accurate, Y not precise, Z precise
• d) X precise, Y accurate, Z precise and accurate

Answer: Both X & Y neither precise nor accurate, Z both precise and accurate.

Question:

• a) 3
• b) 1
• c) 2
• d) 4

Answer: 3

Question: The number of significant figures for the three numbers 161 cm, 0.161 cm, 0.0161 cm are

• a) 3,3 and 3 respectively
• b) 3,4 and 4 respectively
• c) 3,4 and 5 respectively
• d) 3,3 and 4 respectively

Answer:  3,3 and 3 respectively

Question: Given P = 0.0030m, Q = 2.40m, R = 3000m, Significant figures in P, Q and R are respectively

• a) 2, 3, 4
• b) 4, 2, 3
• c) 2, 2, 1
• d) 4, 2, 1

Answer: 2, 3, 4

Question: If the density of a solution is 3.12 g mL^–1, the mass of 1.5 mL solution in significant figures is______.

• a) 4.7 g
• b) 4.680 g
• c) 4680 × 10^–3 g
• d) 46.80 g

Answer: 4.7 g

Question: In which of the following number all zeros are significant?

• a) 50.000
• b) 0.0005
• c) 0.0500
• d) 0.0050

Answer: 50.000

Question: The correctly reported answer of addition of 29.4406, 3.2 and 2.25 will have significant figures

• a) 3
• b) 2
• c) 4
• d) 5

Answer:  3

Question: The number of significant figures in 10.3106 g is

• a) 6
• b) 3
• c) 2
• d) 1

Answer: 6

Question:  Choose the correct option that represents the result of the given calculation to the appropriate number of significant figures

• a) 0.77
• b) 0.7683
• c) 0.768
• d) 0.76

Answer: 0.77

Question: Arrange the numbers in increasing no. of significant figures.

0.002600, 2.6000, 2.6, 0.260

• a) 2.6 < 0.260 < 0.002600 < 2.6000
• b) 2.6000 < 2.6 < 0.002600 < 0.260
• c) 0.260 < 2.6 < 0.002600 < 2.6000
• d) 0.002600 < 0.260 < 2.6 < 2.6000

Answer: 2.6 < 0.260 < 0.002600 < 2.6000

Question: Dimension of pressure are same as that of

• a) Energy per unit volume
• b) Energy
• c) Force
• d) Force per unit volume

Answer: Energy per unit volume

Question: n g of substance X reacts with m g of substance Y to form p g of substance R and q g of substance S. This reaction can be represented as, X + Y = R + S. The relation which can be established in the amounts of the reactants and the products will be

• a) n + m = p + q
• b) p = q
• c) n – m = p – q
• d) n = m

Answer: n + m = p + q

Question: 20 g of CaCO₃ on heating gave 8.8 g of CO₂ and 11.2 g of CaO. This is in accordance with

• a) The law of conservation of mass
• b) The law of constant composition
• c) The law of reciprocal proportion
• d) None of these

Answer: The law of conservation of mass

Question: Which of the following statements is correct about the reaction given below ?

• a) Total mass of iron and oxygen in reactants = total mass of iron and oxygen in product therefore, it follows law of conservation of mass.
• b) Total mass of reactants = total mass of product; therefore, law of multiple proportions is followed
• c) Amount of Fe₂O₃ can be increased by reducing the amount of any one of the reactants (iron or oxygen).
• d) None of these

Answer: Total mass of iron and oxygen in reactants = total mass of iron and oxygen in product therefore, it follows law of conservation of mass.

Question: In an experiment 4.2 g of NaHCO₃ is added to a solution of acetic acid weighing 10.0 g, it is observed that 2.2 g of CO₂ is released into the atmosphere. The residue left behind is found to weigh 12.0 g

• a) law of conservation of mass
• b) law of definite proportions
• c) law of multiple proportions
• d) None of these

Answer: law of conservation of mass

Question: In one experiment, 4g of H₂ combine with 32g of O₂ to form 36g of H₂O. In another experiment, when 50g of H₂ combine with 400g of O₂ then 450g of H₂O is formed. Above two experiments follow

• a) Both
• b) The law of conservation of mass
• c)  The law of constant composition
• d) None of these

Answer:  Both

Question: Irrespective of the source, pure sample, of water always yields 88.89% mass of oxygen and 11.11% mass of hydrogen. This is explained by the law of

• a) constant composition
• b) conservation of mass
• c) multiple proportions
• d) constant volume

Answer: constant composition

Question: The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. The illustrate the law of

• a) constant proportions
• b) multiple proportions
• c) conservation of mass
• d) reciprocal proportions

Answer: constant proportions

Question: The law of definite proportions was given by –

• a) Proust
• b) John Dalton
• c) Humphry Davy
• d) Michael Faraday

Answer: Proust

Question: Which one of the following pairs of compounds illustrate the law of multiple proportions ?

• a) SnCl₂ and SnCl₄
• b) MgO and Na₂O
• c) H₂O and Na₂O
• d) None of these

Answer: SnCl₂ and SnCl₄

Question: Among the following pairs of compounds, the one that illustrates the law of multiple proportions is

• a) CuO and Cu₂O
• b) H₂S and SO₂
• c) NH₃ and NCl₃
• d) CS₂ and FeSO₄

Answer: CuO and Cu₂O

Question: Two samples of lead oxide were separately reduced to metallic lead by heating in a current of hydrogen. The weight of lead from one oxide was half the weight of lead obtained from the other oxide. The data illustrates

• a) law of multiple proportions
• b) law of reciprocal proportions
• c) law of constant proportions
• d) law of equivalent proportions

Answer: law of multiple proportions

Question:  In compound A, 1.00g of nitrogen unites with 0.57g of oxygen. In compound B, 2.00g of nitrogen combines with 2.24g of oxygen. In compound C, 3.00g of nitrogen combines with 5.11g of oxygen. These results obey the following law

• a) law of multiple proportion
• b) law of constant proportion
• c) law of reciprocal proportion
• d) Dalton’s law of partial pressure

Answer: law of multiple proportion

Question: Which of the following statements indicates that law of multiple proportion is being followed.

• a) Carbon forms two oxides namely CO₂ and CO, where masses fo oxygen which combine with fixed mass of carbon are in the simple ration 2 : 1
• b) Sample of carbon dioxide taken from any source will always have carbon and oxygen in the ratio 1 : 2
• c) When magnesium burns in oxygen, the amount of magnesium taken for the reaction is equal to the amount of magnesium in magnesium oxide formed
• d) At constant temperature and pressure 200 mL of hydrogen will combine with 100 mL oxygen to produce 200 mL of water vapour

Answer: Carbon forms two oxides namely CO₂ and CO, where masses fo oxygen which combine with fixed mass of carbon are in the simple ration 2 : 1

Question:  The molecular weight of O₂ and SO₂ are 32 and 64 respectively. At 15°C and 150 mm Hg pressure, one litre of O₂ contains ‘N’ molecules. The number of molecules in two litres of SO₂ under the same conditions of temperature and pressure will be :

• a) 2N
• b) N/2
• c) 1N
• d) 4N

Answer: 2N

Question: 10 dm³ of N₂ gas and 10 dm³ of gas X at the same temperature contain the same number of molecules, the gas X is

• a) CO
• b) NO
• c) CO₂
• d) H₂

Answer: CO

Question: One mole of a gas occupies a volume of 22.4 L. This is derived from

• a) Avogadro’s law
• b) Berzelius’ hypothesis
• c) Gay-Lussac’s law
• d) Dalton’s law

Answer:  Avogadro’s law

Question: One of the following combination which illustrates the law of reciprocal proportions ?

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Equal volumes of two gases A and B are kept in a container at the same temperature and pressure. Avogadro’s law is invalid if

• a) None of these
• b) gas A has more number of molecules than gas B
• c) the gases are non-reactive
• d) the gases are reactive

Answer: None of these

Question: Molecular mass is defined as the

• a) mass of one molecule of any substance compared with the mass of one atom of C-12
• b) mass of one atom compared with the mass of one atom of hydrogen
• c) mass of one atom compared with the mass of one molecule
• d) None of the above

Answer: mass of one molecule of any substance compared with the mass of one atom of C-12

Question:  1 amu is equal to

• a)

  

• b)

  

• c) 1 g of H₂
• d) 1.66 × 10^–23 kg

Answer:

Question: The modern atomic weight scale is based on

• a) C¹²
• b) C¹³
• c) O¹⁶
• d) H¹

Answer: C¹²

Question:

• a) 22.65 %
• b) 32.56 %
• c) 33.65 %
• d) 23.65 %

Answer: 22.65 %

Question:  The average atomic mass of neon based on following data is:

• a) 20.187 u
• b) 18.058 u
• c) 0.33 u
• d) 6.729 u

Answer: 20.187 u

Question: What is the average atomic mass of bromine from the following data : (abundance is in %)

• a) 79.9
• b) 75.9
• c) 76.6
• d) 69.9

Answer: 79.9

Question: What is the mass of an atom of oxygen (in gm)?

• a) 2.656 × 10^–23
• b) 2.0 × 10^–22
• c) 1.567 × 10^–22
• d) 3.5 × 10^–23

Answer:  2.656 × 10^–23

Question: If the mass of the one atom is found to be 2.324784×10^–23g, then this atom can be ?

• a) Nitrogen
• b) Carbon
• c) Oxygen
• d) Fluorine

Answer: Nitrogen

Question: What is the mass of 1 molecule of CO.

• a) 4.65 × 10^–23
• b) 2.895 × 10^–23
• c) 2.325 × 10^–23
• d) 3.732 × 10^–23

Answer: 4.65 × 10^–23

Question: Calculate the volume at STP occupied by 240 gm of SO₂.

• a) 84
• b) 73
• c) 64
• d) 59

Answer: 84

Question: At S.T.P. the density of CCl₄ vapours in g/L will be nearest to:

• a) 6.87
• b) 10.26
• c) 3.42
• d) 4.57

Answer: 6.87

Question: The number of gram molecules of oxygen in 6.02 × 10²⁴ CO molecules is

• a) 5 gm molecules
• b) 0.5 gm molelcules
• c) 10 gm molecules
• d) 1 gm molecules

Answer: 5 gm molecules

Question: The number of oxygen atoms in 4.4 g of CO₂ is

• a) 1.2 × 10²³
• b) 6 × 10²³
• c) 6 × 10²²
• d) 12 × 10²³

Answer: 1.2 × 10²³

Question: Which has maximum number of molecules?

• a) 2 gm H₂
• b) 16 gm O₂
• c) 7 gm N₂
• d) 16 gm NO₂

Answer: 2 gm H₂

Question: Number of atoms in 558.5 gram Fe (at. wt. of Fe = 55.85 g mol^–1) is

• a) twice that in 60 g carbon
• b) 6.023 X 10²²
• c) half that in 8 g He
• d) None of these

Answer: twice that in 60 g carbon

Question: The number of molecules in 16 g of methane is

• a) 6.023 × 10²³
• b) 3.0 × 10²³
• c) Both
• d) None of these

Answer: 6.023 × 10²³

Question: Number of g of oxygen in 32.2 g Na₂SO₄.10 H₂O is

• a) 22.4
• b) 20.8
• c) 2.24
• d) 2.08

Answer: 22.4

Question: The number of moles of oxygen in one litre of air containing 21% oxygen by volume, under standard conditions are

• a) 0.0093 mole
• b) 2.10 mole
• c) 0.21 mole
• d) 0.186 mole

Answer: 0.0093 mole

Question: The number of molecules in 8.96 litre of a gas at 0ºC and 1 atm. pressure is approximately

• a) 24.08 × 10²²
• b) 12.04 × 10²³
• c) 6.023 × 10²³
• d) 18.06 × 10²³

Answer: 24.08 × 10²²

Question: The mass of a molecule of water is

• a) 3 × 10^–26 kg
• b) 2.5 × 10^–26 kg
• c) 3 × 10^–25 kg
• d) 1.5 × 10^–26 kg

Answer: 3 × 10^–26 kg

Question: One mole of CO₂ contains

• a) 6.02 × 10²³ atoms of C
• b) 6.02 × 10²³ atoms of O
• c) 18.1 × 10²³ molecules of CO₂
• d) 3 g atoms of CO₂

Answer: 6.02 × 10²³ atoms of C

Question: Volume of a gas at NTP is 1.12 × 10^–7cm³. The number of molecules in it is

• a) 3.01 × 10¹²
• b) 3.01 × 10²³
• c) 3.01 × 10²⁴
• d) 3.01 × 10²⁰

Answer: 3.01 × 10¹²

Question: How many atoms are contained in one mole of sucrose  (C₁₂H₂₂O₁₁)?

• a) 45 × 6.02 × 10²³ atoms/mol
• b) 20 × 6.02 × 10²³ atoms/mol
• c) 5 × 6.02 × 10²³ atoms/mol
• d) None of these

Answer: 45 × 6.02 × 10²³ atoms/mol

Question: One litre oxygen gas at S.T.P will weigh

• a) 1.43 g
• b) 11.2 g
• c) 2.24 g
• d) 22.4 g

Answer: 1.43 g

Question: Number of moles of NaOH present in 2 litre of 0.5 M NaOH is :

• a) 1.0
• b) 1.5
• c) 2.0
• d) 2.5

Answer: 1.0

Question: O₂, N₂ are present in the ratio of 1 : 4 by weight. The ratio of number of molecules is

• a) 7 : 32
• b) 2 : 1
• c) 1 : 4
• d) 4 : 1

Answer:  7 : 32

Question: How many moles of Al₂(SO₄)₃ would be in 50 g of the substance ?

• a) 0.140 mole
• b) 0.952 mole
• c) 0.083 mole
• d) 0.481 mole

Answer: 0.140 mole