Chemistry

Mole Concept and Stoichiometry

365 Questions

The mole concept is a core area of chemistry focusing on the quantitative relationships between reactants and products in chemical reactions. Questions cover molecular mass calculations, stoichiometric conversions, and determining the number of molecules. This topic is essential for most science entrance and competitive examinations.

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Mole Concept and Stoichiometry Questions

Multiple choice

Which of the following has the largest number of molecules?

  1. 36 g of H2O

  2. 44 g of CO2

  3. 43 g of CH3OH

  4. 54 g of N2O5

  5. 64 g of SO2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Correct answer. Among given options, 36 g of H2O has highest number of molecules. 34 g of H2O = 2 moles of H2O = 2 x 6.022 x 1023 molecules of H2O  

Multiple choice

What is the chemical formula of urea?

  1. NH2CO3

  2. NH2

  3. NH3

  4. (NH2)2 CO
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Urea is an organic compound with the chemical formula (NH2)2CO, commonly produced by the liver and excreted in urine.

Multiple choice

The dipole moment of CO2 is:

  1. 0

  2. 1.84 D

  3. 1.03 D

  4. 1.91
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The dipole moment of carbon dioxide is zero. This is because CO2 is a linear molecule in which the two C=O (m=2.3D) bonds are oriented in opposite directions at an angle of 180°. Due to the linear geometry the dipole moment of one C = O bond cancels that of another. Therefore, the resultant dipole moment of the molecule is zero and it is a non-polar molecule.

Multiple choice

Pure gold is

  1. 22 carat

  2. 100 carat

  3. One carat

  4. 24 carat
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ans : 4.

Multiple choice

Waxy solids alkanes contains

  1. 22 and 27 carbon atoms

  2. Upto 4 carbon atoms

  3. 5 to 19 carbons

  4. Closed loop of Carbon and Hydrogen atoms
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Alkanes, which are the major constituents of crude oil, do not mix with water and float on its surface. The wax that we call paraffin and make candles from is a mixture of alkanes containing between 22 and 27 carbon atoms per molecule.

Multiple choice

What is the molecular mass of water?

  1. 34

  2. 33

  3. 20

  4. 18
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The chemical formula for water is H2O. The atomic mass of hydrogen is approximately 1 and oxygen is 16, so the molecular mass is (2 * 1) + 16 = 18.

Multiple choice

The empirical formula of diamond is?

  1. D

  2. C

  3. Di

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Diamond is a pure form of carbon. Its empirical formula is simply the symbol for carbon, which is C.