Explanation

• The density of gases increases when pressure is increased because gas molecules come closer together.
• Density is the mass per unit volume of a substance.
• When pressure increases, the volume of gas decreases (at constant temperature), causing density to increase.
• This relationship follows Boyle’s Law.

Last verified on 21-06-2026

Explanation

• Vitamin D is essential for healthy bones.
• Its deficiency leads to Rickets in children and Osteomalacia in adults.
• Sunlight is the best natural source of Vitamin D.

Additional information:

Deficiency effects:

• Bone pain
• Weak bones
• Skeletal deformities

Other Vitamin Deficiencies:

• Vitamin A: Night blindness
• Vitamin C: Scurvy
• Vitamin B7 (Biotin): Hair fall

Last verified on 17-01-2026

Explanation

NaCl is a classic example of an ionic compound

Where sodium (Na) loses an electron to become a positively charged ion (cation),

And chlorine (Cl) gains an electron to become a negatively charged ion (an anion).

Formula: NaCl

Molar mass: 58.44 g/mol

IUPAC ID: Sodium chloride

Melting point: 801 °C

Soluble in: Water, Ammonia, Ethanol, Glycerol, Methanol, Propylene glycol, Formic acid, Formamide

Classification: Salt

Boiling point: 1,465 °C

Explanation

Carbon dioxide (CO2) reacts with calcium hydroxide (Ca(OH)2.

It is also known as lime water to form a white precipitate of calcium carbonate (CaCO3), which turns the solution milky:

Ca(OH)2 + CO2 → CaCO3 + H2O

This reaction is often used as a test for carbon dioxide.

Explanation

• Atomic radius decreases along a period as you move from left to right.
• This is because the number of protons in the nucleus increases, which pulls the electrons closer to the nucleus, resulting in a smaller atomic radius.