True-False

Question 11 Mark

State whether the following statement is true or false:
Copper sulphate crystals are always wet due to the presence of water of crystallisation in them.

Answer

False.

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Question 21 Mark

Mg and Mn react with 5% HNO, to form $H_2$(g). [True/ False]

Answer

True.
Explanation:
Nitric acid ($HNO_3$) is a strong oxidising agent. So as soon as hydrogen gas is formed in the reaction it gets oxidised into $HNO_3$ by Nitric acid and it (nitric acid) itself gets reduced into $NO_2, NO_2$ or NO.

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Question 31 Mark

$NO_2$ is acidic oxide. [True/ False]

Answer

True. Explanation: Nitrogen dioxide is an acidic oxide. The reaction with water is,$2\text{NO}_2\ +\ \text{H}_2\text{O}\xrightarrow{\ \ \ \ \ \ \ \ \ }\text{HNO}_3\ +\ \text{HNO}_2$
The extra oxygen is needed as $HNO_2$ is unstable and it oxidises to nitric acid.

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Question 41 Mark

$N_2O$ is called laughing gas. [True/ False]

Answer

True.
Explanation:
Nitrous oxide ($N_2O$), also called dinitrogen monoxide, laughing gas, or nitrous, one of several oxides of nitrogen, a colourless gas with pleasant, sweetish odour and taste.

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Question 51 Mark

All non-metallic oxides dissolve in water to form acids. [True/ False]

Answer

True.
Explanation:
An acidic solution can be formed when a non-metal oxide is dissolved in water. For example, magnesium oxide dissolves to form alkaline solutions. Sulfur dioxide and nitrogen dioxide however, will dissolve to form acidic solutions. Soluble metal oxides produce alkalis when dissolved in water.

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