Questions

There are two types of water hardness: temporary and permanent hardness. Temporary hardness is due to the presence of calcium hydrogen carbonate Ca(HCO3)2(aq) and magnesium hydrogen carbonate Mg(HCO3)2(aq).

1. Ans. A.
98 = 17 + 81
26 = 98 – 72
89 = 26 + 63
35 = 89 – 54
? = 35 + 45, i.e. ? = 80

'Internet' is the shortened form of 'INTERnational-NETwork' which is the interconnected network of all the Web Servers worldwide. It is often called the 'World Wide Web'. 

The dermis is a layer of the skin of the integumentary system. The dermis lies deep to the superficial epidermis which is also the most superficial layer of the skin. The dermis lies superficial to the underlying hypodermis which is also referred to as subcutaneous tissue.

Among the components of the dermis are: sweat glands, hair follicles, collagen fibers, sensory- nerve endings and arrestor pill muscles.