Some elements behave chemically both as metals and nonmetals, and are called metalloids. Their examples include Boron, Silicon, Germanium and Antimony. Elements which are neither metals nor nonmetals are called Noble Gases.

Correct Option: B

Some elements behave chemically both as metals and nonmetals, and are called metalloids. Their examples include Boron, Silicon, Germanium and Antimony. Elements which are neither metals nor nonmetals are called Noble Gases.

Gammexane is an insecticide that is the gamma isomer of benzene hexachloride. It is also known as lindane. Benzene hexachloride is any of several stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexane formed by the light-induced addition of chlorine to benzene.

Correct Option: D

Gammexane is an insecticide that is the gamma isomer of benzene hexachloride. It is also known as lindane. Benzene hexachloride is any of several stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexane formed by the light-induced addition of chlorine to benzene.

Nitrate (NO₃) is the most common form of inorganic nitrogen in unpolluted waters. Nitrate moves readily through soils and into ground water, where concentrations can be much higher than in surface waters. Water in coastal areas mainly contains elementary nitrogen gas (N₂).

Correct Option: B

Nitrate (NO₃) is the most common form of inorganic nitrogen in unpolluted waters. Nitrate moves readily through soils and into ground water, where concentrations can be much higher than in surface waters. Water in coastal areas mainly contains elementary nitrogen gas (N₂).

Alum (Aluminium Sulfate) is used to stop bleeding. For example, Styptic pencils containing aluminium sulfate are used as astringents to prevent bleeding from small shaving cuts. It constricts blood vessels to stop the flow of blood.

Correct Option: B

Alum (Aluminium Sulfate) is used to stop bleeding. For example, Styptic pencils containing aluminium sulfate are used as astringents to prevent bleeding from small shaving cuts. It constricts blood vessels to stop the flow of blood.

On earth, oxygen is the most common element, making up about 47% of the earth’s mass. Silicon is second, making up 28%, followed by aluminum (8%), iron (5%), magnesium (2%), calcium (4%), sodium (3%), and potassium (3%). All of the remaining elements together make up less than 1% of the earth’s mass.

Correct Option: C

On earth, oxygen is the most common element, making up about 47% of the earth’s mass. Silicon is second, making up 28%, followed by aluminum (8%), iron (5%), magnesium (2%), calcium (4%), sodium (3%), and potassium (3%). All of the remaining elements together make up less than 1% of the earth’s mass.