Chemical Reactions and Equations Test - 14

For a reaction to be balanced the amount of all the elements on reactants and product side should be the same (Due to Law of Conservation of Mass).

In option (B) the number of moles of all the elements on the reactants and the product side is Equal.

Hence, option (B) is correct.

The given salt is lead nitrate \({Pb}\left({NO}_{3}\right)_{2}\)

It decomposes to give brown fumes( \({NO}_{2}\) ) and yellow residue( \({PbO}\) ). The reaction can be given as follows:

\(2{Pb}\left({NO}_{3}\right)_{2} \rightarrow 2 {P} {bO}+4 {NO}_{2}+{O}_{2}\)

Hence, option (D) is correct.

For a reaction to be balanced the amount of all the elements on reactants and product side should be the same (Due to Law of Conservation of Mass).

In option (D) the number of moles of all the elements on the reactants and the product side is Equal.

Hence, option (B) is correct.

In order for an element to get oxidised it should either gain an Oxygen or should lose a Hydrogen.

In the reaction we can see that

$\mathrm{CuO}+{\mathrm{H}}_2\stackrel{\text{ heat }}{⟶}\mathrm{Cu}+{\mathrm{H}}_2\mathrm{O}$

Cu atom loses an Oxygen on the reactants side, and in turn reduces and Hydrogen gains an Oxygen Atom on the product side and it gets oxidised.

Hence, option (B) is correct.

\({Pb}+{CuCl}_{2} \longrightarrow {PbCl}_{2}+{Cu}\)

\(Pb\) and \(Cu\) are present in the form of solids whereas \(CuCl_2\)  and \(PbCl_2\) are present in Aqueous form. Therefore, there are two elements present in solid form.

Hence, option (B) is correct.

Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula.

Therefore, amongst the options we can say that in case of formation of vapors the state changes from liquid to vapor and Hence is a Physical Change not a Chemical Change.

Hence option (C) is correct.

The potassium, iodine, lead and nitrate ions dissolve, and the potassium ions react with the nitrate ions to form potassium nitrate while the lead ions react with the iodine ions to form lead iodide. Lead iodide is insoluble in water and precipitates as a bright yellow solid in a double replacement reaction.

Hence, the correct option is (B).

We know that the chemical representation of calcium is \(C a\).

Water is the common name used for the compound with molecular formula \(\mathrm{H}_{2} \mathrm{O}\).

Now let us see the balanced chemical equation for the given reaction.

\(\mathrm{Ca}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Ca}(\mathrm{OH})_{2}+\mathrm{H}_{2}\)

From the above equation, we can see when calcium reacts with water hydrogen and calcium hydroxide are formed as the product of the reaction.

Hence, the correct option is (A).

For a reaction to be balanced the amount of all the elements on reactants and product side should be the same (Due to Law of Conservation of Mass).

In option (B) the number of moles of all the elements on the reactants and the product side is Equal.

Hence, option (B) is correct.

The reactivity series of Metals is given as below:

According to the given table and keeping in mind the order of reactivity of elements 

Zinc can replace iron in a chemical reaction. (Correct Statement)

Silver cannot replace mercury in a chemical reaction. (Correct Statement)

Zinc will displace hydrogen from dilute sulphuric acid. (Incorrect Statement)

Hydrogen shows some chemical properties of metals, so it is included in the activity series. (Correct Statement)

Hence, option (C) is correct.

A combination reaction (also known as a synthesis reaction) is a reaction where two or more elements or compounds (reactants) combine to form a single compound (product). Such reactions are represented by equations of the following form: X + Y → XY.

Options (A), (B), (C) are examples of Combination Reaction whereas  option (D) is an example of Displacement Reaction.

Hence option (D) is correct.

Evolution of gas is represented by  (↑) in a chemical equation.

Substance dissolved in water is  represented by  (aq.) in a chemical equation.

Precipitate substance is represented by (ppt.) in a chemical equation.

Liquid substance is represented by (liq.) or (l) in a chemical equation.

Hence, option (A) is correct.

A double displacement reaction is a type of chemical reaction where two compounds react, and positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products.

In the Reaction:

${\mathrm{BaCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{BaSO}}_4\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)$

The anions $C{l}^{-}$ and $S{O_4}^{2-}$ swap their respective cations when the reaction take place.

Hence, option (D) is correct.

A single displacement reaction is a kind of oxidation-reduction chemical reaction when an ion or element moves out of a compound, i.e., one element is replaced by the other in a compound.

$Fe\left(s\right)+2HCl\left(l\right)\to FeC{l}_2+H_2\left(g\right)$

The anion $C{l}^{-}$ detaches from the Hydrogen atom and combines with the Iron.

Hence, option (A) is correct.

Hydrogen will be represented by (g) as it is a gas.

Carbon monoxide will be represented by (g) as it is a gas.

Gold will be represented by (s) as it is a solid.

Hydrochloric Acid Solution will be represented by (aq.) as it is an aqueous solution.

Hence, option (D) is correct.