2H5 Chemical Changes

When dissolved in water, methylamine forms a solution with a pH of 9. Which statement about methylamine solution is false?

• It has a soapy feeling when touched.

• It turns red litmus paper blue.

• It reacts with calcium carbonate to form carbon dioxide.

• It turns blue when Universal Indicator is added to it.

An incomplete word equation is given below.

-------------------------------  $\rightarrow$  lead nitrate + water 
Which option gives the correct reactants that form the given products?

• lead + nitric acid

• lead carbonate + nitric acid

• lead hydroxide + nitric acid 

• lead sulfate + nitric acid

when sodium nitrate is strongly heated, it forms sodium nitrite and oxygen gas.

This is an example of a _________________ reaction.

• combustion

• electrolysis

• neutralisation

• thermal decomposition

Which substance(s), when reacted with nitric acid, form a gas?

• zinc

• zinc carbonate

• zinc oxide

• zinc hydroxide

Which substance or object can be used to test for the presence of carbon dioxide gas?

• blue litmus paper

• lighted splint

• limewater

• red litmus paper

The pH values of four different solutions are given in the pH scale in the diagram. Which solution will turn blue when Universal Indicator is added to it?

• A

• B

• C

• D

Which option below is most likely to describe a chemical change?

• When a substance is heated, it melts.

• A white solid dissolves in water to form a blue solution.

• When a solid and a liquid are mixed, no visible change occured.

• When a solid was heated, a brown gas was evolved.

The table gives the colours of some indicators at different pH values. Which of the following shows the correct colour of the indicator in distilled water?

• litmus - red, phenolphtalein - colourless, methyl orange- yellow

• litmus - red, phenolphtalein - colourless, methyl orange- red

• litmus - purple, phenolphtalein - colourless, methyl orange- yellow

• litmus - blue, phenolphtalein - pink, methyl orange- yellow

What are the reactants in photosynthesis?

• glucose and oxygen

• carbon dioxide and oxygen

• glucose and water

• carbon dioxide and water

Which statement best describes a neutralisation reaction?

• A solution with a pH of 7 is formed.

• A gas is formed as a product.

• It occurs when an acid is strongly heated.

• It occurs when a metal is added to an acid.