G2013 Q2

 

It takes approximately ______ minutes for sunlight to reach the Earth.

We know that,

Earth-Sun distance = 1.496 x 108m

Velocity of light reaching Earth = 3 x 108 m/s

Time taken by light to reach earth is 

=(Earth-sun distance)/(Velocity of light)  

= (1.496 x 10^8 m)/(3 x 10^8  m/s)

= 8.31 minutes.

G2013 Q1

The number of hydrous minerals in the Moh's scale of hardness is __________.

The hydrous minerals in the Moh’s scale of hardness are

Talc                Mg₃Si₄O₁₀(OH)₂

Gypsum         CaSO₄.2H₂O

Apatite           CaS(PO₄)₃(F₁Cl₁OH)

Topaz             Al₂SiO₄(F₁OH)₂