Practice question (1) CS

Which row identifies diffusion?

• all molecules move in the same direction from higher concentration to lower concentration

• all molecules move in the same direction from lower concentration to higher concentration

• molecules move randomly in all directions from lower concentration to higher concentration

• molecules move randomly in all directions from higher concentration to lower concentration

Amylase in the mouth breaks starch down to maltose. The pH in the mouth is 6.5 and the temperature is 37°C.

(1) changing the pH to 12

(2) increasing the amount of starch

(3) raising the temperature to 45 ℃

(4) removing the maltose as it forms

What would reduce the rate of production of maltose?

• (1) & (3)

• (1) & (4)

• (2) & (3)

• (2) & (4)

Which plant tissues are responsible for the transport of amino acids and which are responsible for the transport of sucrose?

• amino acid = phloem
  sucrose = phloem

• amino acid = phloem
  sucrose = xylem

• amino acid = xylem
  sucrose = xylem

• amino acid = xylem
  sucrose = phloem

Which statements about physical digestion are correct?

• It makes food particles smaller.

• It makes the molecules smaller.

• It occurs in the colon.

• It occurs in the mouth.

Which statement describes a liquid?

• Closely spaced particles able to move freely.

• Closely spaced particles vibrate about a fixed point.

• Particles are far apart and unable to move freely.

• Particles are far apart with large amounts of kinetic energy.

An atom of element X contains 7 electrons. Which statements about atom X are correct?

• X has a mass number greater than 7.

• X is in Group VII of the Periodic Table.

• X is in Period 2 of the Periodic Table.

Which statement about magnesium chloride, MgCl₂, is correct?

• When it is melted it becomes an electrical conductor because its electrons are free to move.

• It consists of anions and cations which have completely filled outer electron shells.

• It has a high melting point because its covalent bonds are very strong.

• The magnesium and chlorine atoms are bonded strongly together by sharing electrons.

Sodium metal reacts with water to produce hydrogen and a solution of sodium hydroxide. In which balanced equation are the state symbols correct?

• 2Na(s) + 2H₂O(aq) → 2NaOH(aq) + H₂(g)

• 2Na(s) + 2H₂O(aq) → 2NaOH(l) + H₂(g)

• 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

• 2Na(s) + 2H₂O(l) → 2NaOH(l) + H₂(g)

The equation for the combustion of hydrogen is shown.

2H₂ + O₂ ---> 2H₂O

Which mass of oxygen reacts when 2 g of hydrogen is burned in excess air?

• 1 g

• 16 g

• 32 g

• 64 g

Which test result identifies oxygen?

• bleaches damp litmus paper

• ‘pops’ with a lighted splint

• relights a glowing splint

• turns limewater milky