Which of the following is an example of a compound?

A compound is a substance formed when two or more elements chemically bond together. Water (H₂O) is a compound made of hydrogen and oxygen.

The smallest unit of an element that retains its chemical properties is called:

An atom is the smallest unit of an element that retains its chemical properties.

Which element is represented by the symbol 'Na'?

The symbol 'Na' stands for Sodium, derived from its Latin name 'Natrium'.

A substance that cannot be broken down into simpler substances by chemical means is a(n):

An element is a pure substance that cannot be broken down into simpler substances by chemical means.

Which of the following is a noble gas?

Noble gases are a group of chemical elements with very low chemical reactivity. Helium is a noble gas.

The chemical formula for table salt (sodium chloride) is:

Table salt is chemically known as sodium chloride, with the formula NaCl.

Which of the following is a diatomic molecule?

A diatomic molecule consists of two atoms. Hydrogen gas (H₂) is a diatomic molecule.

Which element is liquid at room temperature?

Mercury is the only metal that is liquid at room temperature.

The chemical symbol 'K' stands for:

The symbol 'K' stands for Potassium, derived from its Latin name 'Kalium'.

Which of the following is a mixture, not a pure substance?

Air is a mixture of various gases like nitrogen, oxygen, and others.

The number of protons in an atom's nucleus is called the:

The atomic number is the number of protons in an atom's nucleus.

Which element is the most abundant in the Earth's crust by mass?

Oxygen is the most abundant element in the Earth's crust by mass.

Which of the following compounds is commonly known as 'baking soda'?

Baking soda is chemically known as sodium bicarbonate, with the formula NaHCO₃.

Elements in the same group (vertical column) of the periodic table have the same number of:

Elements in the same group of the periodic table have the same number of valence electrons.

Which gas is most abundant in Earth's atmosphere?

Nitrogen makes up about 78% of Earth's atmosphere.

An alloy is an example of:

An alloy is a homogeneous mixture of metals or a mixture of a metal with other elements.

Which of the following is a halogen?

Halogens are a group of elements in the periodic table, and chlorine is a halogen.

The chemical formula H₂O₂ represents:

H₂O₂ is the chemical formula for hydrogen peroxide.

Which particle in an atom has a negative charge?

Electrons are negatively charged particles in an atom.

Which of the following is a physical change?

Melting of ice is a physical change because it does not alter the chemical composition of water.

The element with atomic number 6 is:

The element with atomic number 6 is Carbon.

Which of the following is not a metal?

Silicon is a metalloid, not a metal.

The formula for sulfuric acid is:

The chemical formula for sulfuric acid is H₂SO₄.

Isotopes of an element differ in the number of:

Isotopes of an element differ in the number of neutrons in their nuclei.

Which element is a non-metal that conducts electricity?

Graphite, a form of carbon, is a non-metal that conducts electricity.

The process of a solid changing directly into a gas is called:

Sublimation is the process of a solid changing directly into a gas without passing through the liquid state.

Which of the following is an alkaline earth metal?

Magnesium is an alkaline earth metal, found in Group 2 of the periodic table.

The pH of a neutral solution at 25°C is:

A neutral solution has a pH of 7 at 25°C.

Which element is used in fluorescent lamps and advertising signs due to its bright glow when electrified?

Neon is used in fluorescent lamps and advertising signs due to its bright glow when electrified.

A molecule of ozone contains:

Ozone is a molecule made up of three oxygen atoms (O₃).