Explanation

• A neutron has no electric charge, so it is electrically neutral.

Additional information:

• A proton has a positive charge (+1).
• An electron has a negative charge (−1).

Last verified on 07-10-2026

Explanation

• The atomic number of hydrogen is 1.
• It is the first element on the periodic table. 
• Named by: Antoine Lavoisier (1783)
• Atomic mass: 1.00784 u
• Appearance: Colorless gas
• Symbol: H
• Protons: 1
• Electrons: 1

Last updated 26-07-2026 by NA

Explanation

• The primary component of natural gas is methane (CH4).
• Making up 70% to 90% or more of its composition.
• It is a colorless, odorless, and highly flammable hydrocarbon gas.
• Characteristics: It is a fossil fuel, often found in rock formations alongside oil or on its own. 

Last updated question 15 March2026

Explanation

• Ca is the chemical symbol for calcium.
• Calcium is a chemical element with atomic number 20.
• It is an alkaline earth metal belonging to Group 2 of the periodic table.
• Calcium is essential for strong bones and teeth.

Additional information:

• Na — Sodium
• K — Potassium
• Fe — Iron
• Cu — Copper
• Ag — Silver

Last verified on 10-10-2026

Explanation

• Mercury Symbol: Hg
• Atomic number: 80
• Melting point: -38.83 °C
• Atomic mass: 200.59 u

Last verified on 13-03-2026

Explanation

• The empirical formula of water is H₂O

• Freezing point: 0°C (32°F)
• Boiling point: 100°C
• Molar mass: 18.015 g/mol
• Density: 997 kg/m³
• Melting point: 0°C

Last updated by NA on 25-April-2026

Explanation

Explanation

In the Fahrenheit scale:

• The boiling point of water is 212°F
• The freezing point of water is 32°F

Additional information:

In the Celsius scale:

• Boiling point of water: 100°C
• Freezing point of water: 0°C

Last verified on 02-04-2026

Explanation

• Common salt is chemically known as sodium chloride (NaCl).
• It is an ionic compound composed of sodium and chloride ions
• Representing a 1:1 ratio of sodium and chloride ions
• Formula: NaCl
• Melting point: 801 °C
• Density: 2.16 g/cm³
• Boiling point: 1,465 °C

Question updated on 11-02-2026

Explanation

• A mixture of salt and sand can be separated by dissolving it in water.
• Salt dissolves in water, while sand remains insoluble.
• The sand can then be separated by filtration.
• Finally, evaporation of the water recovers the dissolved salt.

Last verified on 06-10-2026