Write the limitations of chemical equation.

The chemical reaction, 

${\left({\mathrm{NH}}_4\right)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7\stackrel{∆}{\to }{\mathrm{N}}_2+4{\mathrm{H}}_2\mathrm{O}+{\mathrm{Cr}}_2{\mathrm{O}}_3$ is an example of 

ZnCO₃ + 2HCl (aq) ​$\rightarrow$_____ + H₂O(l) + CO₂(g).

In the equation:

$\mathrm{Cu}+{\mathrm{XHNO}}_3\to \mathrm{Cu}({\mathrm{NO}}_3{)}_2+{\mathrm{YNO}}_2+2{\mathrm{H}}_2\mathrm{O}$, the value of $\mathrm{X}$ and $\mathrm{Y}$ are

Consider the following equations.

$\mathrm{Pb}\left({\mathrm{NO}}_3{)}_2\right(\mathrm{aq}) +2\mathrm{KI} (\mathrm{aq}) \to {\mathrm{Pbl}}_2(\mathrm{w}) +2{\mathrm{KNO}}_3$(x)

$\mathrm{Zn}\left(\mathrm{y}\right) +{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right) \to {\mathrm{ZnSO}}_4\left(\mathrm{aq}\right) +{\mathrm{H}}_2\left(\mathrm{z}\right)$

What are w, x, y and z in the above equations?

Complete the following equation.

2KBr(aq)+BaCl₂(aq)$\rightarrow$_____(aq)+BaBr₂(aq)

${\mathrm{FeS}}_2$ is converted into ${\mathrm{Fe}}_2{\mathrm{O}}_3$ according to the following equation:

$4{\mathrm{FeS}}_2+{\mathrm{xO}}_2\to 2{\mathrm{Fe}}_2{\mathrm{O}}_3+{\mathrm{ySO}}_2$

$\mathrm{x}$ and $\mathrm{y}$ used in the equation have the values:

Consider the following statements.

I. A chemical equation tells us about the substances involved in a reaction.

II. It gives information about the symbols and formula of substances involved in a reaction.

III. It tells us about the atoms or molecules of the reactants and products involved in a reaction.

The correct statement(s) is/are

When balancing the equation with polyatomic ions, ${\mathrm{CaSO}}_4+{\mathrm{NaNO}}_3\to \mathrm{Ca}({\mathrm{NO}}_3{)}_2+{\mathrm{Na}}_2{\mathrm{SO}}_4$, you need to modify the coefficient of _____ molecule.

(A) ${\mathrm{NaNO}}_3$     (B)${\mathrm{CaSO}}_4$     (C) ${\mathrm{Na}}_2{\mathrm{SO}}_4$

Enter your correct answer as A, B or C.

Balance the following equation by identifying the name of the missing molecule:

Calcium hydroxide $+$ _____ $\to$ Calcium carbonate$+$Water

$2{\mathrm{NaHCO}}_3\stackrel{∆}{\to }$_____$+ {\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2$

(A) ${\mathrm{Na}}_2{\mathrm{CO}}_3$                     (B) $\mathrm{Na}$                       (C) ${\mathrm{Na}}_2\mathrm{O}$

Enter your correct answer as A, B or C.