I) Choose the correct answers:-
1) The most reactive metal is
a) Copper b) silver c) potassium d) calcium
2) The metal which is liquid at room temperature is
a) Sodium b) bromine c) calcium d) mercury
3) Which one of the following metal is the most ductile?
a) Aluminium b) copper c) sodium d) Gold
4) Which one of the following metal is most reactive and stored in kerosene?
a) Iron b) Gold c) Copper d)Potassium
5) Name the gas evolved when magnesium reacts with dilute hydrochloric acid.
a) Chlorine b) Oxygen c) Hydrogen d) Nitrogen
6) Which metal reacts readily with cold water?
a) Gold b) Silver c) Magnesium d) Calcium
7) Out of these, which one is more reactive with water?
a) Sodium, b) Magnesium c) Iron d) Copper
Answers
1. The most reactive metal is
a) Copper b) silver c) potassium d) calcium
Explanation : potassium is the most reactive metal among them because it is the element of first group of periodic table. first group is also known as Alkali metals.
Therefore potassium is the most reactive metal. hence option (c) is correct.
2. The metal which is liquid at room temperature is
a) Sodium b) bromine c) calcium d) mercury
Explanation : mercury is the only metal that is liquid at room temperature. bromine is also liquid at room temperature but it is non-metal.
Therefore mercury is liquid at room temperature, hence option (d) is correct.
3. Which one of the following metal is the most ductile?
a) Aluminium b) copper c) sodium d) Gold
Explanation : Gold is the most ductile less reactive metal. It is used as ornaments due to glittering properties.
Therefore gold is the most ductile metal. hence option (d) is correct.
4. Which one of the following metal is most reactive and stored in kerosene?
a) Iron b) Gold c) Copper d)Potassium
Explanation : We've already explained that potassium is Alkali metal. It is one of the most reactive metal in periodic table. It burns in air so we stored it in kerosene.
Therefore potassium is the most reactive and stored in kerosene. hence option (d) is correct.
5. Name the gas evolved when magnesium reacts with dilute hydrochloric acid.
a) Chlorine b) Oxygen c) Hydrogen d) Nitrogen
Explanation : when magnesium reacts with dilute hydrochloric acid, it evolves hydrogen gas and produces magnesium chloride.
i.e., Mg + 2HCl ⇒ MgCl₂ + H₂↑
Therefore hydrogen gas is evolved when magnesium reacts with dilute hydrochloric acid. hence option (c) is correct.
6. Which metal reacts readily with cold water?
a) Gold b) Silver c) Magnesium d) Calcium
Explanation : It is calcium, it reacts with cold water and form calcium hydroxide which is also known as quicklime.
chemical reaction is given by,
Ca + 2H₂O ⇒ Ca(OH)₂ + H₂ ↑
Therefore the calcium reacts readily with cold water. hence option (d) is correct.
7. Out of these, which one is more reactive with water?
a) Sodium b) Magnesium c) Iron d) Copper
Explanation : sodium is more reactive with water. actually sodium is one of the most reactive element in the periodic table. It reacts with water and form sodium hydroxide ( a strong base) and liberates hydrogen gas.
i.e., 2Na + 2H₂O ⇒ 2NaOH + H₂ ↑
Therefore sodium is more reactive with water. hence option (a) is correct.
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