Which is the only gem of world made of a single element?

Correct Answer: Phosphorous

Explanation:

A nitrogenous base is an element that contains nitrogen that have same chemical properties of the base.

Correct Answer: Diamond

Explanation:

Here in the given options, Diamond is an element as it is the allotrope of the carbon atom.

Correct Answer: 0

Explanation:

NH3, Ammonia is a neutral compound as the individual oxidation numbers elements that make up the compound NH3 are Nitrogen (N) and Hydrogen (H) sum to zero. 

We do not speak of the oxidation number of a molecule. We can speak of the oxidation numbers of the individual elements that make up the compound.

 

Here the oxidation number of Nirogen is -3 and that of Hydrogen is +1.

Now, NH3 = 1(-3) + 3(+1) = -3 + 3 = 0.

Correct Answer: 'M' is used as a unit of molarity and stands for mole per litre ie, number of moles of solute per liter of solution

Correct Answer: H and Br

Explanation:

Only H and Br form Polar Covalent Bond.

 

Covalent bonding:

Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.

1. Polar Covalent Bond

2. Nonpolar Covalent Bond

 

1. Polar Covalent Bond:

A Polar Covalent Bond is created when the shared electrons between atoms are not equally shared. This occurs when one atom has a higher electronegativity than the atom it is sharing with. The atom with the higher electronegativity will have a stronger pull for electrons (Similiar to a Tug-O-War game, whoever is stronger usually wins). As a result, the shared electrons will be closer to the atom with the higher electronegativity, making it unequally shared.

 

2. Nonpolar Covalent Bond:

A Nonpolar Covalent Bond is created when atoms share their electrons equally. This usually occurs when two atoms have similar or the same electron affinity. The closer the values of their electron affinity, the stronger the attraction. This occurs in gas molecules; also known as diatomic elements. Nonpolar covalent bonds have a similar concept as polar covalent bonds; the atom with the higher electronegativity will draw away the electron from the weaker one.

 

Here H and H and N and N form Non-polar covalent bonds. Na and Br form the ionic bond.

Correct Answer: Avogadro's law

Correct Answer: atomic number

Explanation:

Atomic number is the serial number of an element in the periodic classification of elements. It gives the number of protons and also the number of electrons in an atom.

Correct Answer: Rayon

Explanation:

Terylene and nylon are synthetic fibres produced by a process of polymerisation. Terylene is a polyester and nylon, a poyamide.

Silk is purely a natural product obtained from silk worms.

Rayon is a man-made material which consists of purified cellulose in the form of long fibres. Cellulose occurs in the cell wall of plants. Rayon fibre is chemically identical to cotton but has a shine like silk. Since it is  basically derived from a natural source (cellulose) it is called a regenerated fibre.

Correct Answer: 40

Correct Answer: atomic number