Chemical Reaction

Which of the following describes best about chemical reaction?

• The process in which substances are chemically converted to a substance

• The process in which substances are chemically converted to substances with similar properties to the their original substances

• The process in which substances are chemically converted to different substances with different properties

• The process in which substances are chemically converted to substances that can turn into the original states

When water is heated, it turns into steam. Is this a chemical reaction? Why?

• Yes, because changes in states are chemical changes

• Yes, because a new substance is formed

• No, because changes in states are physical changes

• No, because a new formed substance has similar properties to their original substances

Which of the following is caused by chemical reactions?

• Changes in shape

• Changes in size

• Changes in states

• Changes in properties

Which of the following is different from others?

• Salt farming

• Using baking powder in making cake

• Turning on a cooking gas stove

• Taking antacids to neutralize acids in stomach

Which of the following demonstrates a chemical reaction?

• Boiling water

• Lighting incense sticks

• Melting ice cubes

• Subliming mothballs

Which of the following does not involve chemical reactions?

• Precipitating

• Gas bubble formation

• Color change

• Uniform composition

Which of the following is a chemical reaction?

• Salt dissolved in water

• Food spoilage

• Melting ice-cream

• Crystallization sauce

Which of the following gases cause a reaction that produces water?

• Oxygen and hydrogen

• Nitrogen and hydrogen

• Oxygen and nitrogen

• Nitrogen and carbon dioxide

Which of the following reactions does not correspond to the law of conservation of mass?

• In an open container, the reaction between hydrochloric acid and sodium hydroxide produced sodium chloride and water.

• In a closed container, the reaction between nitric acid and calcium hydroxide yielded calcium nitrate and water.

•  In a closed container, the reaction between zinc and sodium hydroxide made sodium zincate and hydrogen.

• In an open container, the reaction between magnesium and hydrochloric acid produced magnesium chloride and hydrogen.

Which of the following reactions make their surroundings hot?

• Reduction reactions

• Oxidation reactions

• Endothermic reactions

• Exothermic reactions