Question

Sodium metal reacts with water to produce hydrogen gas.

Answer 1

Answer:

Q1: A single replacement reaction takes place because sodium is more reactive than hydrogen.

Explanation:

Answer 2

Answer:

Q1. D) A single replacement reaction takes place because sodium is more reactive than hydrogen.

Explanation: $2Na+2H_2O\rightarrow 2NaOH+H_2$ Sodium metal reacts with water to givesodium hydroxide and hydrogen gas. A single replacement reaction takes place because sodium is more reactive than hydrogen.  

Sodium easily lose electrons than hydrogen and get oxidized to $Na^+$ and $H^+$ get reduced to give $H_2$ .

Q2. B) It is a single replacement reaction, and the cations in the two ionic compounds are different.

Explanation: $3Na+AlCl_3\rightarrow 3NaCl+Al$ where Sodium is a metal and $AlCl_3$ is an ionic compound. Na being more reactive than Al, displaces it from its salt solution.

Q3. D) $Zn+H_2SO_4\rightarrow ZnSO_4+H_2$

Explanation: A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.Thus zinc can easily lose electrons as compared to hydrogen and result in the formation of zinc sulfate and hydrogen.

Q4. False

$Zn+CaCl_2\rightarrow$no reaction

Explanation: As zinc lies lower in reactivity series, it is less reactive than calcium. It will not be able to displace calcium from its salt and hence no reaction occur. Thus the given statement is false.

Q5. False

Explanation: A double displacement reaction is one in which exchange of ions take place.  Thus an element replaces another element and not same element.

A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution. Thus one element should be different from another element.

Q6. A)$Na_3PO_4+3KOH\rightarrow 3NaOH+K_3PO_4$, because K retains the same charge throughout the reaction

Explanation: A balanced chemical reaction is one in which the number of atoms on both sides of a chemical equation are same. Also K has an oxidation state or charge of +1 in $KOH$ as well as $K_3PO_4$