the nitrates of alkali metals which one cannot be decomposed to its oxide

To determine which nitrate of alkali metals cannot be decomposed to its oxide, we need to consider the properties of alkali metals and their nitrates.

1. Alkali metals: Alkali metals include elements such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). These metals are highly reactive and have a tendency to lose electrons to form positive ions.

2. Nitrates: Nitrates are compounds that contain the nitrate ion (NO3-). They are typically soluble in water and can undergo decomposition reactions under certain conditions.

Now, let's examine the nitrates of alkali metals:

• Lithium nitrate (LiNO3): Lithium nitrate can be decomposed to its oxide (Li2O) when heated strongly. Therefore, it is not the nitrate that cannot be decomposed to its oxide.

• Sodium nitrate (NaNO3): Sodium nitrate can also be decomposed to its oxide (Na2O) when heated strongly. Therefore, it is not the nitrate that cannot be decomposed to its oxide.

• Potassium nitrate (KNO3): Potassium nitrate can be decomposed to its oxide (K2O) when heated strongly. Therefore, it is not the nitrate that cannot be decomposed to its oxide.

• Rubidium nitrate (RbNO3): Rubidium nitrate can be decomposed to its oxide (Rb2O) when heated strongly. Therefore, it is not the nitrate that cannot be decomposed to its oxide.

• Cesium nitrate (CsNO3): Cesium nitrate is the nitrate of alkali metals that cannot be decomposed to its oxide. When heated strongly, it decomposes to form cesium nitrite (CsNO2) and oxygen gas (O2), rather than its oxide.

In conclusion, among the nitrates of alkali metals, only cesium nitrate (CsNO3) cannot be decomposed to its oxide.