GCSE GCSE Combined Science 3

Question 1

What is the difference between a covalent bond and a metallic bond?

Accepted Answer

A covalent bond involves sharing electrons between non-metals; metallic bonds involve delocalised electrons in a lattice of metal ions

Answer

Both involve transferring electrons

Answer

A metallic bond involves sharing electrons

Answer

Covalent bonds only occur in ionic compounds

Question 2

What is the difference between series and parallel circuits?

Accepted Answer

In series, current flows in one path; in parallel, current can flow through multiple paths simultaneously

Answer

In series, components share current; in parallel, current splits

Answer

Series circuits have more voltage

Answer

Parallel circuits always have less resistance

Question 3

What is natural selection?

Accepted Answer

The process by which organisms with favourable traits are more likely to survive, reproduce, and pass on those traits

Answer

Humans selecting the best organisms to breed

Answer

Random changes in DNA

Answer

The formation of new species overnight

Question 4

What is the equation for calculating work done?

Accepted Answer

Work = force × distance

Answer

Work = mass × acceleration

Answer

Work = power × time

Answer

Work = energy ÷ time

Question 5

What is the difference between a physical and a chemical change?

Accepted Answer

Physical changes are always reversible; chemical changes produce new substances and are usually irreversible

Answer

Chemical changes are reversible; physical changes are not

Answer

They are the same

Answer

Physical changes only occur in liquids

Question 6

What does the pH scale measure?

Accepted Answer

The acidity or alkalinity of a solution (1 = strong acid, 7 = neutral, 14 = strong alkali)

Answer

The strength of an electric current

Answer

The density of a substance

Answer

The boiling point of a liquid