Balance the following chemical equation and identify the type of chemical reaction.

 $\mathrm{Na} \left(\mathrm{s}\right)+\mathrm{S}\left(\mathrm{s}\right) \stackrel{\mathrm{Fuse} }{\to } {\mathrm{Na}}_2\mathrm{S}\left(\mathrm{s}\right)$

Balance the following chemical equation and identify the type of chemical reaction.

 ${\mathrm{TiCl}}_4 \left(\mathrm{l}\right)+\mathrm{Mg} \left(\mathrm{s}\right) \stackrel{ }{\to } \mathrm{Ti} \left(\mathrm{s}\right)+2 {\mathrm{MgCl}}_2 \left(\mathrm{s}\right)$

Balance the following chemical equation and identify the type of chemical reaction.

 $\mathrm{CaO} \left(\mathrm{s}\right)+{\mathrm{SiO}}_2 \left(\mathrm{s}\right) \stackrel{ }{\to } {\mathrm{CaSiO}}_3 \left(\mathrm{s}\right)$

Balance the following chemical equation and identify the type of chemical reaction.

 ${\mathrm{H}}_2{\mathrm{O}}_2 \left(\mathrm{l}\right) \stackrel{ \mathrm{UV} }{\to } {\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)+{\mathrm{O}}_2 \left(\mathrm{g}\right)$

A magnesium ribbon is burnt in oxygen to give a white compound $\mathrm{X}$ accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound $\mathrm{Y}$.

Write the chemical formula of $\mathrm{X}$ and $\mathrm{Y}$.

A magnesium ribbon is burnt in oxygen to give a white compound $\mathrm{X}$ accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound $\mathrm{Y}$.

Write a balanced chemical equation, when $\mathrm{X}$ is dissolved in water.

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.

Why do silver articles turn black when kept in the open for a few days?

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.

Name the black substance formed and give its chemical formula.