Among the following the electron deficient compound is(a) BCl3 (b) CCl4 (c) PCl5 (d) BeCl2

To determine which compound is electron deficient among BCl3, CCl4, PCl5, and BeCl2, we need to analyze the electron configuration and bonding of each compound.

(a) BCl3: Boron (B) has an atomic number of 5, and its electron configuration is 1s2 2s2 2p1. Boron forms three covalent bonds with chlorine (Cl) atoms, resulting in a trigonal planar molecular geometry. Since boron only has three valence electrons and forms three bonds, it is considered electron deficient.

(b) CCl4: Carbon (C) has an atomic number of 6, and its electron configuration is 1s2 2s2 2p2. Carbon forms four covalent bonds with chlorine (Cl) atoms, resulting in a tetrahedral molecular geometry. Carbon has four valence electrons and forms four bonds, so it is not electron deficient.

(c) PCl5: Phosphorus (P) has an atomic number of 15, and its electron configuration is 1s2 2s2 2p6 3s2 3p3. Phosphorus forms five covalent bonds with chlorine (Cl) atoms, resulting in a trigonal bipyramidal molecular geometry. Phosphorus has five valence electrons and forms five bonds, so it is not electron deficient.

(d) BeCl2: Beryllium (Be) has an atomic number of 4, and its electron configuration is 1s2 2s2. Beryllium forms two covalent bonds with chlorine (Cl) atoms, resulting in a linear molecular geometry. Beryllium has only two valence electrons and forms two bonds, so it is considered electron deficient.

Therefore, among the given compounds, the electron deficient compound is (d) BeCl2.