Chemistry Questions

In chemistry, a metal is an element that readily forms positive ions (cations) and has metallic bonds. Metals are opaque, lustrous elements that are good conductors of heat and electricity. Most metals are malleable and ductile and are, in general, denser than the other elemental substances.

Examples of metals are aluminium, copper, iron, tin, gold, lead, silver, titanium, uranium, and zinc.

Here Se - Selenium is an element but is not a metal, S - Sulphur is not a metal and I - Iodine is also not a metal.

Hence, Zn - Zinc is the only metal in the given options.

Electronegativity refers to the ability of an atom to attract shared electrons in a covalent bond. The higher the value of the electronegativity, the more strongly that element attracts the shared electrons.

Electronegativity increases from bottom to top in groups, and increases from left to right across periods. Thus, fluorine is the most electronegative element and lithium is the least.

The halogens make up group 17 in the periodic table.

They are five elements:

Chlorine (Cl)

Fluorine (F)

Bromine (B)

Iodine (I)

Astatine (At).

But astatine is not purely halogen as it is radioactive.

Milk is not a pure substance since it has so many constituents that can be separated physically.

Compounds are pure substances formed from elements unlike mixtures.

Vitamins are essential nutrients found in foods. They perform specific and vital functions in a variety of body systems, and are crucial for maintaining optimal health.

The two different types of vitamins are fat-soluble vitamins and water-soluble vitamins.

Fat-soluble vitamins :

 Vitamins A, D, E and K — dissolve in fat before they are absorbed in the bloodstream to carry out their functions. Excesses of these vitamins are stored in the liver, and are not needed every day in the diet.

Water-soluble vitamins :

Vitamins dissolve in water and are not stored by the body. Since they are eliminated in urine, we require a continuous daily supply in our diet. The water-soluble vitamins include the vitamin B-complex group and vitamin C.

Water-soluble vitamins are easily destroyed or washed out during food storage or preparation.

The gram formula mass of a compound is nothing but the molar mass.

The molar mass of K2CO3 (Potassium Carbonate) is given by

Atomic weights of individual elements are

K (Potassium) = 39 g

C (Carbon) = 12 g

O (Oxygen) = 16 g

Hence, that of K2CO3 = 39(2) + 12 + 16(3)

= 78 + 12 + 48

= 138.

chemical energy is contained in the chemical bonds between the reactants in the chemical compounds.

Covalent bonds hold atoms together because the attraction between the positively charged nuclei and the negatively charged shared electrons is greater than the repulsions between the nuclei themselves.