PHYSCI Q1

Which of the following is the first stage in the life cycle of a star?

• Supernova

• Protostar

• Main sequence

• Red giant

What marks the end of a star’s life cycle?

• Fusion of hydrogen

• The formation of a neutron star

• The end of fusion in the core

• The expansion of the outer layers

The process of nuclear fusion in stars primarily converts:

• Helium into hydrogen

• Hydrogen into helium

• Oxygen into carbon

• Nitrogen into hydrogen

Which element is most likely to form a stable ion with a charge of +1?

• Oxygen

• Sodium

• Magnesium

• Chlorine

A molecule of methane (CH₄) contains:

• One carbon atom and four hydrogen atoms

• Four carbon atoms and one hydrogen atom

• Two carbon atoms and two hydrogen atoms

• One carbon atom and two hydrogen atoms

Which of the following represents an ionic bond?

• NaCl

• H₂O

• CO₂

• CH₄

Which of the following molecules is non-polar based on electronegativity difference?

• H₂O

• CO₂

• NH₃

• HF

A molecule with an electronegativity difference of 1.7 is likely to be:

• Non-polar

• Polar covalent

• Ionic

• Metallic

Which of the following molecules is polar?

• O₂

• Cl₂

• CH₄

• HCl

A molecule with an electronegativity difference of 0.4 is likely to be:

• Non-polar

• Polar covalent

• Ionic

• Metallic