Explanation

• The modern periodic table arranges elements in order of increasing atomic number.
• The atomic number is the number of protons present in the nucleus of an atom.
• Elements with similar chemical properties are placed in the same group (vertical column).
• The modern periodic law was established by Henry Moseley.

Last verified on 12-10-2026

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