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Form 1 Chemistry Water and Hydrogen Questions and Answers
State two reasons why hydrogen is not commonly used as a fuel.
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1.
In an experiment, rods of metals P, Q and R were cleaned with sand paper and placed in a beaker containing water. Another set of rods was also cleaned and placed in a beaker containing dilute acid. After placing the rods in two liquids bubbles of gas were seen around some of the rod as shown in the diagrams below. (a) Why is it necessary to clean the rods with sand paper before dipping them into
2.
A student set up an experiment below to collect gas K. The glass wool was heated before heating zinc powder. (a) Why was it necessary to heat the moist glass wool before heating zinc powder? (b) What would happen if the zinc powder was heated before heating the glass wool? (c) What property of gas K makes it possible for it to be collected as shown in the diagram?
3.
study the set up below and answer the questions that follow: (a) Write an equation for the reaction, which takes place in the combustion tube. (b) What property of gas Z allow it to be collected as shown in the diagram?
4.
When a candle was burnt completely, the total mass of products was found to be greater than the original mass of the candle. Explain.
5.
Study the diagram below and answer the question that follows. Describe one chemical test that can be carried out to identify substance S.
6.
An experiment was set up as shown in the diagram below: (a) Identify substance D (b) Describe how the other product of the burning candle could be prevented from getting into environment
7.
A student used the set up shown in the diagram below in order to study the reactions of some metals with steam. The experiment was carried out for ten minutes. (a) What observation would be made if gas F is ignited? (b) When the experiment was repeated using iron powder instead of magnesium ribbon, very little gas F was obtained. (i) Give a reason for this observation (ii) What change in the
8.
State two reasons why hydrogen is not commonly used as a fuel.
9.
The set up below was used to investigate the products of burning biogas( methane). Study it and answer the questions that follow. (a) What product will be formed in test tube Y (b) State and explain the observations which will be made in Z.
10.
The set-up below was used to investigate the reaction between dry hydrogen gas and copper (II) oxide. (a) Name substance A (b) State the observation made in the combustion tube (c) Explain the observation stated in (b) above.
11.
(a) A student used fig 2 to investigate the action of dilute sulphuric (VI) acid on some metals. Beaker I and II contained equal volumes of dilute sulphuric (VI) acid. To beaker I, a clean rod was dipped and to beaker II, a clean copper rod was dipped. (i) Why was it necessary to clean the metal rods? (ii) Describe the observations made in each beaker. Beaker I Beaker II (iii) Explain observation
12.
Study the set-up in figure 6 and answer the question that follow. (a) Name the substance that was collected in tube P. (b) Write an equation for the reaction which occurs in tube Q in the first few minutes of the experiment. (c) Give a suitable conclusion for the experiment in the setup.
13.
Hydrogen gas can be prepared by passing steam over heated magnesium ribbon as shown in figure 2. (a) Write an equation for the reaction that produces hydrogen gas. (b) Explain why the delivery tube must be removed from the beneath the water before heating is stopped. (c) Explain why solution metal is not suitable for this experiment.
14.
The diagram below represents a set-up that was used to react lithium with water. Study it and answer the questions that follow: (a) Write an equation for the reaction that takes place, given that the atomic number of lithium is 3. (b) Why would it not be advisable to use potassium in place of lithium in the above setup?
15.
(a) Candle wax is mainly a compound consisting of two elements. Name the two elements (b) The set up below was used to investigate the burning of a candle. Study it and answer the questions that follow. (i) What would happen to the burning candle if the pump was turned off? Give reasons. (ii) State and explain the changes in mass that are likely to occur in tube N by the end of the experiment.
16.
(a) Zinc reacts with hydrochloric acid according to the following equation. #Zn(s)+2HCl(aq) to ZnCl_2(aq)+H_2(g)# Identify the reducing agent. Give a reason for the answer. (b) Iron sheets are dipped in molten zinc to prevent rusting. Name this process.
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