Chemistry Questions

The Law of Definite Proportion states that the same compound, wherever found or however made, always contains the same elements combined together in the same fixede ratio by weight.

Moles of solute present in 1 litre or 1000ml of solution is called molarity

Fractional distillation is the process of seperation of a mixture of two or more liquids into the different fractions, which differ fairly widely in their boiling points. The liquid with a lower boiling point will be vaporized first and hence would be the distillate (first fraction). Eg. Ethyl alcohol has a boiling point of 78.10C and water 1000C. When a mixture of these two liquids is heated, alcohol vaporizes first and is collected separately as the distillate. 

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.

The paste applied to the side of a match box is a mixture of phosphorus trisulphide, glass powder (or sand) to cause friction and glue (binding material)

Normality is a way of expressing concentration of a solution and can be calculated by the formula-

Normality (N) = No. of gram equivalent of solute/ volume of solution (in litre)

Gram equivalent weight of H2 SO4 = Molecular weight/ No. of Hydrogen atom = 98/2 = 49 gm

No. of gram equivalent in 49 gm of H2 SO4 = 1

So, Normality in 1 litre of solution = 1/1 = 1 N

Steel is not a compound or element. Steel is an alloy of iron and carbon and other elements and hence it is a mixture. Because of its high tensile strength and low cost, it is a major component used in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons.