MCQs on P-Block Elements

Ans. (C) Si

Explanation: Boron and Silicon, both of them have similar atomic values and ionization energy. Both show the properties of non-metallic elements. Boron and Silicon both are semiconductors. The acids, like H3BO3 and H4SiO4, formed by Boron and Silicon are weak. Chloride of Boron and Silicon can be hydrolyzed easily. Hence, Boron shows diagonal relation with Silicon.

Ans. (b) Carbon

Explanation: The property of self-linked atoms of any element is called Catenation. It forms chains or rings of different structures. When it comes to Carbon, the process of Catenation is completely natural. Carbon forms covalent bonds which form longer structures with the help of other carbon atoms. Apart from Carbon, Silicon, Boron is also on this list.

Ans. BF₃

Explanation: BF₃ can be counted as an electrophile as Boron has three electrons which are coupled with the three electrons that come from the three atoms of hydrogen. Hence, there is total of six electrons in the outer shell. Therefore, to get a stable octet structure, it receives another couple of electrons from a nucleophile.

Ans. (b) BCl₃

Explanation: Lewis Acids are those chemical species with vacant orbitals, which can receive electron pairs from the Lewis Bases. It is described by the concept of Lewis's theory of acid-base relations. BCl₃ is the stronger Lewis Acid among the above mentioned, as it has 3p orbitals on Cl, which is greater than the 2p orbitals on B. Hence, the orbital overlap is less efficient.

Ans. (a) F₂

Explanation: Fluorine is one of the most electronegative elements. So, the formation of F is definitely the most energetic and compatible of the standard reductions. Hence Fluorine is the strongest oxidizing agent. Fluorine is so strong that it reacts even with water.

Ans. (c) 3

Explanation: Meta-phosphoric acid is an eroding, inorganic, cyclic polyphosphate. It is created by the bonded phosphoric acid units. We know that this acid is the oxo-acid of phosphorus, that can form a double bonding with O atom. It can also form a single bond with the OH group. Hence, the number of P-O-P bonds of cyclic metaphosphoric acid is 3. Have a look at the picture below to understand better.

Ans. (b) Nitrous oxide

Explanation: Nitrous oxide can be obtained on heating ammonium nitrate at 250°C. Let’s have a look at the equation below to understand this perfectly.

NH₄NO₃ → N₂O + 2H₂O

Ans. (d) 4

Explanation: Atomicity can be defined as the number of atoms that are present in a single molecule. This can be categorized into four kinds- Monatomic, Diatomic, Tri-atomic, and Tetra-atomic. In the case of tetra-atomic, mostly the molecules of the element include four atoms of the same element. Hence, their atomicity is 4. Phosphorus is a tetra-element molecule, so its atomicity is 4.

Ans. (b) sp³d²

Explanation: Hybridization can be described as the technique of mixing two atomic orbitals to create a new type of orbital that is hybridized. These new formations have completely distinguished shapes and energies. The hybridized sp³d² includes – 1 s, 3 p, and 2 d. Hence, it undergoes the combination of 6 identical sp³d² hybrid orbitals.

Ans. (d) H₃PO₃ -tribasic

Explanation: The acid that can donate three hydrogen ions to a base during the acid-base reaction is called a tribasic acid. Similarly, if acid has two hydrogen ions to donate, is can be identified as a dibasic acid. In this case, H₃PO₃ has two hydrogens are attached to the oxygen atoms. Hence, it is a dibasic acid.

Ans. (c) Pyrophosphoric acid

Explanation: The acid that can donate four hydrogen ions to a base during acid-base reaction is called a tetrabasic acid. Pyrophosphoric acid (Hâ,,Pâ,,Oâ‡), has four hydrogens attached to the oxygen atoms. Hence, this is a tetra-basic acid. The structure looks like the following picture.

Ans. (b) P

Explanation: To remove an electron from an atom, we need a certain amount of energy. This amount of energy is called ionization energy. As we go down towards the periodical table, this amount keeps decreasing. Similarly, this ionization energy differs from left to right to the periodical table. Now, imagine all the above-mentioned elements as per their places in the periodical table, and if you observe carefully, the position of P in the periodical table gives it the maximum ionization potential among these.

Ans. (c) Iodine

Explanation: Generally, we know that seawater is salty. It is because of its Iodine content. The upper layer of the seawater contains the maximum amount of Iodine, whereas freshwater has a very low iodine count. Interestingly, even after this huge Iodine count, the seawater only contains 0.8% of total Iodine on the Earth’s crust.

Ans. (b) square planar

Explanation. There are 4 electron bond pairs and two lone pairs in Xe atom. As the result of undergoing the sp³d² hybridisation, it represents octahedral electron and square planner molecular geometry. We will understand this more clearly by observing the following image.

Ans. (c) NI₃

Explanation. We know that basicity of any element is actually the tendency to supply a lone pair so that both remains basic. As iodine has vacant orbital- d, it can receive long-paired electrons from nitrogen to help in back bonding. The structure of Nl₃ looks like the picture below.