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A signature written with carbon pencil weighs 1 mg. What is the number of carbon atoms present in the signature?

A. 6.02 × 1020 B. 0.502 × 1020 C. 5.02 × 1023 D. 5.02 × 1020 Solution: (B) 1 mg = 1 × 10−3 g 12... View Article

The mass of one mole of electron is;

A. 9.1 × 10−28 g B. 0.55 mg C. 9.1 × 10−24 g D. 6 × 10−12 g Solution: (B) We know, Mass of 1... View Article

Calculate the total number of protons in 10g of calcium carbonate is (N0 = 6.023 × 1023):

A. 3.01×1024 B. 4.06×1024 C. 2.01×1024 D. 3.02×1024 Solution: (A) 1 mole of CaCO3 = 20 × 1 + 6 × 1... View Article

How many moles of magnesium phosphate, Mg₃(PO₄)₂ will contain 0.25 mole of oxygen atoms?

A. 0.02 B. 3.125 x 10-2 C. 1.25 x 10-2 D. 2.5 x 10-2 Solution: (B) In one molecule of magnesium phosphate, 8 oxygen atoms are present.... View Article

The value of amu is which of the following?

A. 1.57 × 10−24 kg B. 1.66 × 10−24 kg C. 1.99 × 10−23 kg D. 1.66 × 10−27 kg Solution: (D)... View Article

In the following questions, two statements are given, one is Assertion (A) and the other is Reason (R). Examine the statements carefully and mark the correct answer according to the instructions given below:

Assertion: Equal moles of different substances contain the same number of constituent particles. Reason: Equal weights of different substances... View Article

Law of constant composition is same as the law of:

A. Conservation of mass B. Conversation of energy C. Multiple proportion D. Definite proportion Solution: (D) Law of definite... View Article

Gram molecular volume of oxygen at STP is;

A. 3200 cm3 B. 5600 cm3 C. 22400 cm3 D. 11200 cm3 Solution: (C) Gram Molecular volume is the volume occupied by 1 mole of molecules and... View Article

Which one of the following has maximum number of oxygen atoms?

A. 2 g of water B. 2 g of sulphur dioxide C. 2 g of carbon dioxide D. 2 g of carbon monoxide Solution: (A) Number of atoms present in... View Article

The number of gram molecules of chlorine in 6.02×1025 hydrogen chloride molecules is;

A. 5 B. 50 C. 100 D. 10 Solution: (C) 1 Mole of HCl = 1 + 35.5 = 36.5 = 6.023 × 1023 Number of gram molecules = 6.02 ×... View Article

Number of atoms of He in 100u of He (atomic wt of He is 4) are;

A. 25 B. 100 C. 50 D. 100 × 6 × 10−23 Solution: (A) No.ofatoms= Mass of substance / Atomic mass = 100 / 4 = 25 Atoms... View Article

0.1 mole of a carbohydrate with empirical formula CH₂O contains 1g of hydrogen. What is its molecular formula?

A. C5H10O5 B. C6H12O6 C. C4H8O4 D. C3H6O3 Solution: (A) Let molecular formula be (CH2O)n In one mole of carbohydrate, hydrogen... View Article

80g of oxygen contains as many atoms as in;

A. 80g of hydrogen B. 1g of hydrogen C. 10g of hydrogen D. 5g of hydrogen Solution: (D) Oxygen atom contains 16 g of oxygen 80g of... View Article

Mass of 0.1mole of methane is;

A. 1g B. 16g C. 1.6g D. 0.1g Solution: (C) Mass of one mole of methane (CH4) = 16g Mass of 0.1 mole of methane = 16 × 0.1g = 1.6g.... View Article

The number of formula units of calcium fluoride, CaF₂ present in 146.4g of CaF₂ (the molar mass of CaF₂ is 78.08g/mol) is.

A. 1.129 × 1024CaF2 B. 1.146 × 1024CaF2 C. 7.808 × 1024CaF2 D. 1.877 × 1024CaF2 Solution: (A) CaF2 = 146.4g... View Article

The percentage weight of Zn in white vitriol [ZnSO₄.7H₂O] is approximately equal to (at.mass of Zn = 65, S = 32, 0 = 16 and H = 1)

A. 33.65 % B. 32.56 % C. 23.65 % D. 22.65 % Solution: (D) Molecular weight of white vitriol [ZnSO4.7H2O] = 65 + 32 + (4 × 16) +... View Article