3 Pure C1, C2, C3

Which apparatus can be used to measure a volume of 20.0 cm³ of solution?

I. pipette

II. burette

III. measuring cylider

IV. beaker

• II only

• I and II only

• II and III only

• II and IV only

Gas X can be prepared by the following apparatus.

What ca you deduce about gas X?

I. It is less dense than air.

II. It is denser than air.

III. It is insoluble in water.

IV. It is soluble in water.

• I and III

• I and IV

• II and III

• II and IV

A food dye is analysed by paper chromatography, giving the chromatogram shown:

What is the Rf value of the dye represented by the spot at 8.0 cm?

• 0.60

• 0.67

• 0.75

• 0.80

A mixture which contains a liquid and a soluble solid may be separated by evaporation. Which of the following is a disadvantage of this method?

• It always requires heating

• The liquid must have a high boiling point.

• The solute recovered may contain impurities.

• It cannot be used for a solid with a low melting point.

A scientist suspected that some red lentils might be added with two artificial colour additives, X and Y.

He extracted a concentrated sample of liquid from the lentils using water and developed the chromatogram to find a single spot of dye X. He repeated the experiment using ether and obtained a single spot of Y. He repeated the experiment with ethanol and finally managed to identify X and Y in the lentil sample.

What can you conclude about X and Y?

• Y is soluble in water, but X is insoluble

• X is soluble in ethanol, but Yis insoluble

• Y is soluble in water, but insoluble in ether

• Y is soluble in ethanol, but insoluble in ether

A gas Y was made from a reaction and collected by passing through a U-tube immersed in an ice mixture. The gas condensed into a colourless liquid.

What could be the melting and boiling points of Y?

• A

• B

• C

• D

Which ion does not have the same number of electrons as an atom of argon?

• S^2-

• Cl^-

• Ca²⁺

• Al³⁺

Balloons are usually made of latex, which is a poroud material that allows gas molecules to move in and out.

An inflated balloon when placed in liquid nitrogen (melting pt: -210^oC, boiling pt: - 196^oC), deflates quickly, and when it is removed, inflates again quickly.

Which statement best explains this observation?o

• The warmer air particles diffuse out of the balloon very quickly

• The air particles contract when there is a decrease in temperature.

• A decrease in temperature reduces the attractive force of the air particles.

• A decrease in temperature decreases the kinetic energy of the air particles.

Z-85 and Z-87 are isotopes of an element Z.

How is the ion formed by Z-85 different form the ion formed by Z-87?

• It has 2 less neutrons and 2 less electrons

• It has 2 less neutrons but no less electrons

• It has 2 less protons and 2 less electrons

• It has 2 less protons but no less electrons

Which process gives out heat energy and involves the largest change in volume?

• Boiling

• Condensation

• Freezing

• Sublimation