Questions

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 tenant farmer is one who resides on land owned by a landlord. These farmers would have to share the yield with the landowner in a process known as sharecropping. In the South, these farmers need to have their own tools and animals.

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. 

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.

In the above options, sperms are the haploid cells. In humans, haploid cells are those have only half the number of usual number of chromosomes. Sperm, gamates and egg cells are the haploid cells examples.

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