NEET Practice Questions (MCQs) with Answers & Solutions

Barium chloride (BaCl2) gives a white precipitate of barium sulfate (BaSO4) when mixed with a sulfate solution. Additionally, barium ions impart a green color to the flame during a flame test.

When ammonia ($NH_3$) reacts with hydrogen chloride ($HCl$), it forms ammonium chloride ($NH_4Cl$), which appears as white dense fumes. The reaction can be represented as: $NH_3 + HCl ightarrow NH_4Cl$.

The blue borax bead test is a qualitative test for the presence of cobalt. When borax is heated with cobalt, it forms a blue-colored bead due to the formation of cobalt borate. Hence, cobalt is responsible for the blue borax bead.

Boron compounds, such as trimethyl borate ($B(OMe)_3$), impart a green color to the burner flame. This is a characteristic flame test for boron.

Phosphine ($PH_3$) is a colorless gas with a smell of rotten fish. It is a compound of phosphorus and hydrogen.

When $MnO_2$ and $H_2SO_4$ are added to NaCl, chlorine gas ($Cl_2$) is liberated. This reaction is a redox reaction where $MnO_2$ acts as an oxidizing agent and oxidizes $Cl^-$ ions from NaCl to form $Cl_2$ gas.

Nitric oxide (NO) combines with Fe(II) ions to form a brown complex. The reaction is as follows: $$Fe^{2+} + NO ightarrow [Fe(NO)]^{2+}$$ This complex is brown in color.