NCERT Class 11 Chemistry Part 1 Chapter 1

Term

DefinitionDefine Chemistry. The branch of science that studies the preparation, properties, structure, and reactions of material substances.

What is the Law of Conservation of Mass?

Matter can neither be created nor destroyed.

State the Law of Definite Proportions.

A given compound always contains exactly the same proportion of elements by weight.

What is the Law of Multiple Proportions?

If two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in simple whole number ratios.

State Avogadro's Law.

Equal volumes of all gases at the same temperature and pressure contain equal number of molecules.

What is Dalton's Atomic Theory?

Matter consists of indivisible atoms; atoms of an element are identical; compounds form from fixed combinations of atoms; atoms are neither created nor destroyed.

What is the SI unit of mass?

Kilogram (kg)

What is the SI unit of amount of substance?

Mole (mol)

Convert 1 L to cm³.

1 L = 1000 cm³

What is 1 amu (atomic mass unit)?

1 amu = 1.66056 × 10⁻²⁴ g

What is Avogadro's Number?

6.022 × 10²³ entities/mol

Define molar mass.

The mass of one mole of a substance, in grams.

Density formula?

Density = Mass / Volume

Scientific notation of 0.00016?

1.6 × 10⁻⁴

Scientific notation of 232.508?

2.32508 × 10²

1 mole of water contains how many molecules?

6.022 × 10²³ molecules of H₂O

Empirical vs Molecular formula?

Empirical shows simplest ratio, Molecular shows actual number of atoms in a molecule.

Molar mass of H₂O?

18.02 g/mol

Mass percent formula?

Mass % = (mass of element / molar mass of compound) × 100

Example: Mass % of H in H₂O?

11.18%

Example: Mass % of O in H₂O?

88.79%

1 mol NaCl contains how many formula units?

6.022 × 10²³ units

Three states of matter?

Solid, Liquid, Gas

Define pure substance.

A substance with all particles of the same chemical nature.

Define mixture.

Contains two or more substances mixed in any ratio.

Difference between homogeneous and heterogeneous mixture?

Homogeneous: uniform composition; Heterogeneous: non-uniform composition.

Define physical property.

A property measured without changing substance identity (e.g., color, boiling point).

Define chemical property.

A property that involves a substance's ability to undergo change (e.g., reactivity).

What is precision?

Closeness of measurements to each other.

What is accuracy?

Closeness of a measurement to the true value.

SI prefix for 10⁻³?

Milli (m)

SI prefix for 10⁻⁶?

Micro (μ)

SI prefix for 10³?

Kilo (k)

SI prefix for 10⁶?

Mega (M)

Rules for significant figures - non-zero digits?

All non-zero digits are significant.

Are leading zeros significant?

No, they just indicate position.

Are zeros between non-zero digits significant?

Yes.

Are trailing zeros significant?

Only if there is a decimal point.

Balanced equation for CH₄ combustion?

CH₄ + 2O₂ → CO₂ + 2H₂O

Define limiting reagent.

The reactant that is completely used up and limits the amount of product formed.

What is molarity?

Number of moles of solute per litre of solution (mol/L)

What is molality?

Number of moles of solute per kg of solvent (mol/kg)

What is empirical formula of CH₂Cl with MM 98.96?

Empirical = CH₂Cl, Molecular = C₂H₄Cl₂

What is the mass of 1 mole of CH₄?

16 g/mol

What is the average atomic mass of carbon?

12.011 u

Difference between atom and molecule?

Atom: single smallest unit of an element; Molecule: two or more atoms bonded together.