Questions

To make steel, iron ore is first mined from the ground. It is then smelted in blast furnaces where the impurities are removed and carbon is added.

In simple, steel is iron alloyed with carbon, usually 0 - 2%.

The axial skeleton is the part of the skeleton that consists of the bones of the head and trunk of a vertebrate. In the human skeleton, it consists of 80 bones and is composed of six parts; the skull bones, the ossicles of the middle ear, the hyoid bone, the rib cage, sternum and the vertebral column.

Bones of shoulder, thigh and foot are the part of appendicular skeleton. 

Hence, Vertebral column is the part of axial skeleton.

DNA is not a single stranded and does not have amino acids. Hence options, b & C are eiminated. Dna is a double helix structure containing nucleobase—either cytosine (C), guanine (G), adenine (A), or thymine (T)—as well as a monosaccharide sugar called deoxyribose and a phosphate group. 

True, poorly controlled stress and anger can lead to heart attacks and strokes.

The law of conservation of mass states that in any closed system the mass of the system is neither created nor destroyed over time i.e, the mass cannot be changed overtime.

Hence, the given statement is true.

A devastating  series of earthquakes in 1906 ruined the city completely and its presence is a constant remainder of the past and a threat of repetition in future.

Fiords are along narrow inlets into the sea-coast with steep sides. It usually occurs along the coast of a mountainous region.It has been formed by glacial action.