Chemistry 2018 Waec Past Questions and Answers

Question 26 :

• WAEC 2018

The diagram above illustrates a conical flask containing water and ice. Which of the following is correct about the diagram?

A. The water is at lower temperature than the ice
B. Energy is absorbed when the ice changes to water
C. Energy is released when the ice changes to water
D. The water molecules vibrate about a fixed point

Question 27 :

• WAEC 2018

Which of the following statements best explains the difference between a gas and a vapour?

A. Unlike gases, vapours are liquids at room temperature
B. Unlike gases, vapour can easily be condensed into liquids
C. Unlike gases, vapour is readily converted into solids
D. Vapours are generally denser than gases

Question 28 :

• WAEC 2018

Consider the following reaction equation: \(2HCl + Ca(OH)_{2} \to CaCl_{2} + H_{2}O\). What is the volume of 0.1\(moldm^{-3}\) HCl that would completely neutralize 25\(cm^{3}\) of 0.3\(moldm^{-3}\) Ca(OH)\(_{2}\)?

A. 150\(cm^{3}\)
B. 75\(cm^{3}\)
C. 30\(cm^{3}\)
D. 25\(cm^{3}\)

Question 29 :

• WAEC 2018

\(Cu\) and \(HNO_{3}\) are not suitable for preparing hydrogen gas because of their

A. Reactivity and oxidation respectively
B. Conductivity and corrosiveness respectively
C. Melting point and reduction respectively
D. Electronegativity and solubility respectively

Question 30 :

• WAEC 2018

Which of the following CANNOT be an empirical formula?

A. \(CH\)
B. \(CH_{2}\)
C. \(P_{2}O_{5}\)
D. \(N_{2}O_{4}\)