Periodic Classification and Elements

The valency in a formula can be explained on the cris-cross basis. Hence, the number of electrons in the outermost shells of A and B would be 5 and 2, respectively.

Atomic spectroscopy is the determination of elemental composition by its electromagnetic or mass spectrum. Atomic spectroscopy is closely related to other forms of spectroscopy.

A quintuple bond in chemistry is an unusual type of chemical bond first reported in 2005 for a dichromium compound. Quadruple bonds are rarer but occur especially for Cr, Mo, W, and Re. In a quintuple bond, ten electrons participate in bonding between the two metal centers.

This option is correct as there are 14 elements in actinoids series, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No and Lr

The carbides of the group 4, 5 and 6 transition metals (with the exception of chromium) are often described as interstitial compounds.These carbides have metallic properties and are refractory. Some exhibit a range of stoichiometries, e.g. titanium carbide, TiC. Titanium carbide and tungsten carbide are important industrially and are used to coat metals in cutting tools.

U is the chemical symbol for Uranium, a radioactive element used in nuclear fuel and weapons. Chemical symbols are standardized internationally by IUPAC, with U representing this element on the periodic table.

Yes, the number of shells present in an atom decides the period to which it belongs.

Ni is the chemical symbol for nickel, a transition metal used in coins, stainless steel, and batteries. Nitrogen is N, phosphorus is P, and camphor is an organic compound, not an element.

Rb is the chemical symbol for Rubidium, an alkali metal in group 1. Rhodium is Rh, Radium is Ra, and none of these is incorrect since B is right.

B is the chemical symbol for boron. Barium has the symbol Ba, and bismuth has the symbol Bi. Chemical symbols are either one or two letters and are derived from the element's English or Latin name.

Hydrogen (H) is the most abundant element in the universe, making up about 75% of all normal matter by mass. Helium (He) is second most abundant. Silicon (Si) is common on Earth but not in the universe.

In a neutral atom, the number of electrons equals the number of protons. This balance of positive and negative charges gives the atom its overall neutral charge. If there are 11 protons, there must be 11 electrons for neutrality.

Isotopes are atoms of the same element with identical proton counts but different neutron counts. This gives them the same chemical properties but different atomic masses. Isobars have same mass number, compounds are combinations of elements, and allotropes are different structural forms of the same element.

Equanil (meprobamate) has the chemical formula C4H12CaN2O4 as the calcium salt, containing Carbon, Hydrogen, Oxygen, and Nitrogen. The presence of nitrogen is indicated by the 'amate' suffix (carbamate). Carbon and Hydrogen alone (A) is insufficient, C-H-O (B) lacks the nitrogen, and C-H-O-N-S (D) incorrectly adds sulfur.