Question 1
An element N has the electron arrangement 2.8.6 and mass number of 32.
- How many protons does element N have?
- What is the number of neutrons in the nucleus of N
- What type of bond would be formed between N and oxygen
Answer
- 16
- 32 - 16 = 16
- Covalent bond
Question 2
Study the table below and use the information to answer the question that follows
Describe how you would separate the solids from their mixture
Answer
- Put the mixture in hot water and stir where A and C dissolves.
- Filter to separate insoluble B the solution of A and C is cooled to precipitate / separate C
- Then filter the resulting mixture to separate C from A
- The remaining solution of A is evaporated to obtain solid A
- Filter to separate insoluble B the solution of A and C is cooled to precipitate / separate C
- Then filter the resulting mixture to separate C from A
- The remaining solution of A is evaporated to obtain solid A
Question 3
Explain why the luminous flames of the Bunsen burner appear yellow
Answer
Incomplete combustion produces carbon particles. The carbon particles glow in presence of heat producing the characteristic yellow colour
Question 4
A student set up the experiment below to collect gas K. The glass wool was heated before heating the Zinc powder.
- Why was it necessary to heat the moist glass wool before heating Zinc powder
- What would happen if the Zinc powder was heated before heating the glass wool
- What property of gas K makes it possible for it to be collected as shown in the diagram
Answer
- To generate steam which pushes out air
- The air would oxidize Zinc to Zinc oxide / or no gas would be obtained
- It is less dense than air
Question 5
2.12 grams of anhydrous sodium carbonate are dissolved in 200.0cm3 water. 25.0cm3 of this solution neutralize 80.0cm3 of hydrochloric acid solution. Calculate the concentration of hydrochloric acid (in mol/dm3)
Answer
