- Amal Augustine
- January 22, 2026
What is Molarity in Chemistry with Examples: Formula & Easy Explanation for NEET, JEE & CUET
Understanding concentration is essential in chemistry, and one of the most commonly used concentration terms is molarity. To clearly understand what is molarity in chemistry with examples, we must first look at how solutions are prepared and measured in laboratories and real-life applications. In what is molarity in chemistry with examples, molarity helps chemists express how much solute is present in a given volume of solution, making it a vital concept in solution chemistry.
Definition of Molarity
In what is molarity in chemistry with examples, molarity is defined as the number of moles of solute dissolved per litre of solution. It is represented by the symbol M and mathematically written as:
Molarity (M)=Number of moles of soluteVolume of solution in litres\text{Molarity (M)} = \frac{\text{Number of moles of solute}}{\text{Volume of solution in litres}}
This definition forms the basis of understanding what is molarity in chemistry with examples, especially for aspirants preparing for school exams, NEET, JEE, and CUET.
Why Molarity Is Important
In what is molarity in chemistry with examples, molarity is widely used because it directly connects the amount of substance to the volume of solution. Chemical reactions often occur in solutions, and knowing molarity helps calculate how much reactant is required or produced. When learning what is molarity in chemistry with examples, aspirants realise that molarity is essential in titrations, acid–base reactions, and stoichiometric calculations.
However, molarity depends on the volume of solution, which can change with temperature. This means molarity is temperature-dependent, unlike molality.
Simple Examples of Molarity
To better understand what is molarity in chemistry with examples, let us consider a simple case.
If 1 mole of sodium chloride (NaCl) is dissolved in water to make 1 litre of solution, the molarity of the solution is 1 M.
Another example:
If 0.5 moles of glucose are dissolved to form 2 litres of solution, the molarity is:
M=0.52=0.25 MM = \frac{0.5}{2} = 0.25 \text{ M}
These examples clearly explain what is molarity in chemistry with examples using basic calculations.
Molarity in Acid–Base Solutions
Acids and bases are commonly expressed in terms of molarity. For instance, a 1 M hydrochloric acid (HCl) solution contains 1 mole of HCl in 1 litre of solution. Understanding what is molarity in chemistry with examples is crucial in titration problems where molarity is used to find unknown concentrations.
For example, if 0.1 M NaOH reacts with 0.1 M HCl, equal volumes will neutralise each other because the molar concentrations are the same.
Molarity in Everyday Life
Molarity is not limited to laboratories. Medical saline solutions, intravenous fluids, and disinfectants are prepared using molarity concepts. Learning what is molarity in chemistry with examples helps aspirants see how chemistry connects with healthcare and industry.
For example, glucose solutions used in hospitals are prepared with specific molarity to ensure they are safe for the human body.
Calculating Molarity from Mass
Another common numerical problem involves calculating molarity using mass. To understand what is molarity in chemistry with examples, consider this:
If 5 g of NaOH (molar mass = 40 g/mol) is dissolved to make 250 mL solution:
Moles of NaOH = 5 ÷ 40 = 0.125
Volume = 0.25 L
M=0.1250.25=0.5 MM = \frac{0.125}{0.25} = 0.5 \text{ M}
Such calculations are extremely common in exams.
30 MCQs on What is Molarity in Chemistry with Examples
1.
The molarity of HNO₃ in a sample having density 1.4 g/mL and mass percentage 63% is ____ (M.W. HNO₃ = 63)
a) 14
b) 10
c) 7
d) 12
Answer: a
2.
A 100 mL solution is made by adding 1.43 g of Na₂CO₃·xH₂O. The normality is 0.1 N. Value of x is:
a) 10
b) 20
c) 5
d) 9
Answer: a
3.
Mole fraction of glucose in an aqueous binary solution is 0.1. Mass percentage of water (nearest integer) is:
a) 47%
b) 37%
c) 63%
d) 53%
Answer: a
4.
6.023×10²² molecules are present in 10 g of substance X. Molarity of solution containing 5 g of X in 2 L is ____ ×10⁻³:
a) 25
b) 5
c) 30
d) 40
Answer: a
5.
At 300 K, vapour pressure of a solution with 1 mol n-hexane + 3 mol n-heptane is 550 mm Hg. If 1 more mol n-heptane is added, vapour pressure increases by 10 mm Hg. Vapour pressure of pure n-heptane is:
a) 600
b) 400
c) 200
d) 300
Answer: a
6.
Two open beakers: one has pure solvent, other has solution of same solvent with non-volatile solute. Both sealed in container. Over time:
a) Volume of solution decreases & solvent increases
b) Volume of solution unchanged & solvent decreases
c) Volume of solution increases & solvent decreases
d) Both volumes unchanged
Answer: c
7.
A graph of vapour pressure vs temperature for liquids X, Y, Z is shown. Correct inference(s):
a) (A)
b) (B)
c) (C)
d) (A) and (C)
Answer: b
8.
For a solution with two components: density d (g mL⁻¹), molarity C₂ and mole fraction χ₂ of component 2, C₂ is:
a) C2=1000χ2M1+χ2(M2−M1)C_2=\frac{1000\chi_2}{M_1+\chi_2(M_2-M_1)}
b) C2=dχ2M2+χ2(M2−M1)C_2=\frac{d\chi_2}{M_2+\chi_2(M_2-M_1)}
c) C2=1000dχ2M1+χ2(M2−M1)C_2=\frac{1000d\chi_2}{M_1+\chi_2(M_2-M_1)}
d) C2=1000dχ2M2+χ2(M2−M1)C_2=\frac{1000d\chi_2}{M_2+\chi_2(M_2-M_1)}
Answer: c
9.
Hardness of water containing 10⁻³ M MgSO₄ expressed as CaCO₃ equivalents (ppm) is:
a) 100
b) 200
c) 20
d) 10
Answer: a
10.
10.30 mg of O₂ dissolved in 1 L sea water (density 1.03 g/mL). Concentration of O₂ in ppm is:
a) 10
b) 20
c) 30
d) 40
Answer: a
11.
Cylinder contains ideal gas (0.1 mol in 1.0 dm³) in thermal equilibrium with 0.5 molal ethylene glycol solution at its freezing point. When stoppers withdrawn, final gas volume (L) is:
a) 2.18
b) 1.18
c) 0
d) 4
Answer: a
12.
Which is a reversible sol?
a) Gelatin solution
b) As₂S₃ solution
c) Fe(OH)₃ solution
d) Gold solution
Answer: a
13.
Maximum amount of a solid solute dissolving in a given amount of solvent does not depend upon:
(i) Temperature (ii) Nature of solute (iii) Pressure (iv) Nature of solvent
a) i and iii
b) only ii
c) ii and iv
d) only iii
Answer: d
14.
Molality of aqueous solution of any solute having mole fraction 0.25 is:
a) 18.52 m
b) 16.67 m
c) 33.33 m
d) 9.26 m
Answer: a
15.
Vapour pressures of pure liquids A and B are 400 and 800 mm Hg at T°C. Mole fraction of A in solution whose boiling point is T°C is:
a) 0.4
b) 0.1
c) 0.8
d) 0.2
Answer: b
16.
Molarity of solution containing 8 g NaOH in 250 mL water is:
a) 0.2 M
b) 0.4 M
c) 0.8 M
d) 1.0 M
Answer: c
17.
If active mass of a 6% solution of a compound is 2, its molecular weight is:
a) 30
b) 15
c) 60
d) 22
Answer: a
18.
Molarity of NaOH solution made by dissolving 0.4 g NaOH to make 500 mL solution is:
a) 0.02 M
b) 0.05 M
c) 0.04 M
d) 0.08 M
Answer: a
19.
Concentration of fluorine in ppm in 500 g toothpaste containing 0.2 g fluoride is:
a) 2×10³
b) 4×10³
c) 8×10³
d) 4×10²
Answer: d
20.
10 g NaOH dissolved to make 500 mL solution. Molarity is:
a) 0.5×10⁻³ M
b) 0.4 M
c) 0.25×10⁻³ M
d) 0.05 M
Answer: d
21.
A 40% HCl solution has density 1.2 g mL⁻¹. Molarity is nearly:
a) 11 M
b) 12 M
c) 13 M
d) 14 M
Answer: c
22.
Density of oxygen gas at 5 atm and 127°C is:
a) 2.80 g/L
b) 4.88 g/L
c) 1.49 g/L
d) 5.60 g/L
Answer: b
23.
Molarity of 0.2 N Na₂CO₃ solution is:
a) 0.05 M
b) 0.1 M
c) 0.2 M
d) 0.4 M
Answer: b
24.
Density of 2 M aqueous NaOH is 1.28 g/cm³. Molality is:
a) 1.20 m
b) 1.56 m
c) 1.67 m
d) 1.32 m
Answer: c
25.
In water saturated air, mole fraction of water vapour is 0.02. Total pressure is 1.2 atm. Partial pressure of dry air is:
a) 1.18 atm
b) 1.76 atm
c) 1.176 atm
d) 0.98 atm
Answer: c
26.
Mixture of NaCl and K₂Cr₂O₇ heated with conc. H₂SO₄ gives deep red vapours. Which statement is false?
a) Vapours give yellow solution with NaOH
b) Vapours contain CrO₂Cl₂ only
c) Vapours contain CrO₂Cl₂ and Cl₂
d) Vapours passed into lead acetate in acetic acid give yellow ppt
Answer: c
27.
Molarity of 1 L solution containing 22.2 g CaCl₂ is:
a) 0.4 M
b) 0.2 M
c) 0.8 M
d) 0.6 M
Answer: b
28.
If molarity of Cu²⁺ ions is 3×10⁻⁴, express in ppm:
a) 0.3
b) 0.2
c) 0.1
d) 0.6
Answer: a
29.
Liquids M and N form an ideal solution. Vapour pressures of pure M and N are 450 and 700 mm Hg. Correct statement:
a) XMXN>YMYN\frac{X_M}{X_N} > \frac{Y_M}{Y_N}
b) XMXN=YMYN\frac{X_M}{X_N} = \frac{Y_M}{Y_N}
c) XMXN<YMYN\frac{X_M}{X_N} < \frac{Y_M}{Y_N}
d) XM−YM<XN−YNX_M – Y_M < X_N – Y_N
Answer: a
30.
Molality of 20% (mass/mass) aqueous KI solution (Molar mass KI = 166 g/mol) is:
a) 1.48
b) 1.51
c) 1.35
d) 1.08
Answer: b
Conclusion on What is Molarity in Chemistry with Examples
Amal Augustine is the founder of ExQuizMe, a dynamic learning and quiz platform built to make education engaging, competitive, and fun. A passionate learner and an academic achiever, Amal completed his schooling at Government HSS Manjapra, graduating with 92.5% in Computer Science. He later earned his degree from St. Stephen’s College, University of Delhi, one of India’s most prestigious arts and science institutions.
Currently, Amal is pursuing his Master’s degree at National Sun Yat-sen University, Taiwan, where he continues to deepen his interest in research and technology. Throughout his school and college years, he won 50+ national-level interschool and collegiate quiz competitions, was
Beyond academics, Amal Augustine is an avid reader of science journals, a dedicated research student, and a technology enthusiast who loves programming and exploring the world of Computer Science. Through ExQuizMe, he aims to make learning accessible, enjoyable, and empowering for students across the globe.