Answer : The correct option is, (2) Cr (Chromium)
Explanation :
The reactivity series of metal are arranged of the reactivity from the highest to the lowest. Reactivity series is used to determine the products of the single displacement reactions. In the single displacement reaction, the most reactive metal displaces the least reactive metal.
From the given reactivity series we conclude that there are two metal (Mg and Cr) are more reactive metal than the Ni and there are two metal (Pb and Cr) are less reactive metal than the Zn. So, the Cr (Chromium) is the metal which is more active than Ni and less active than Zn.
Hence, the correct option is, (2) Cr
9 amino acids (alanine, cysteine, glycine, isoleucine, leucine, methionine, phenylalanine, proline, valine) have no hydrogen donor or acceptor atoms in their side chains.
1. d. Water is able to dissolve non-polar gases like oxygen and carbon dioxide.
2. d. -4.8 degree Celsius
3. a. Each solution has the same number of relative particles of solute per kilogram of solvent.
Answer: 16700 Joules
Explanation:
The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

Q = Heat absorbed = ?
m = mass of sand = 2 kg
c = heat capacity = 
Initial temperature =
= 
Final temperature=
= 
Change in temperature ,
Putting in the values, we get:


16700 J of energy must be added to a 2-kilogram pile of it to increase its temperature from 40°C to 50°C
Answer:
Some of the properties of cobalt silicate include:
It occurs as a crystal with red- violet type colour.
The shape of the cobalt silicate crystal is orthorhombic.
The molecular weight of cobalt silicate is 209.95.
The melting temperature of Cobalt Silicate is 1618 degrees Celsius.
The density of Cobalt Silicate is 4.63 grams per centimetre cube.
Cobalt Silicate can serve as a semi-conductor.