Explanation

Concrete drying is a continuous and fluid event, and usually reaches its full effective strength after about 28 days.

Explanation

Liquified HCl has been cooled until the gas turns into a liquid.

ND06-08-2023

Explanation

Except at the magnetic pole, the Earth's magnetic field is always horizontal

 the horizontal component of the earth's magnetic field is zero at the magnetic poles.

Hence, Earth's magnetic field always has a horizontal component except at the magnetic poles where it is zero.

Explanation

Photo resistors  are light sensitive variable resistors 

فوٹو ریزسٹرز روشنی کے حساس متغیر ریزسٹرس ہیں۔

Explanation

 Gallium is a chemical element.

Atomic Number of Gallium is 31

Explanation

 Gallium is a chemical element.

Atomic Number of Gallium is 31

Explanation

Tungsten is a greyish-white lustrous metal, which is a solid at room temperature.

74 is the atomic number of Tungsten.

Explanation

Chlorophyll is a compound that is called a Chelate. 

Photosynthesis depends on the presence of chlorophyll for the absorption of light.

There are about five closely related chlorophylls:

1. chlorophyll a
2. chlorophyll b
3. chlorophyll c
4. chlorophyll d
5. chlorophyll e
6. chlorophyll f

Explanation

Silicon is an element found in glass, cement, China Clay and Quartz. 

Silicon is a chemical element with the symbol Si and atomic number 14.

MUG 10-12-2022

ND5-07-2023

Explanation

Answer: 

C: Heating of Mercuric oxide powder: The heating of Mercuric oxide powder is a permanent change. We cannot get powder by revere reaction so it is a chemical change

Sublimation of Iodine: It is a physical change

Heating a platinum wire in a Bunsen flame: Platinum is a noble gas that cannot change its physical appearance after heating. So it is not a chemical change

Evaporation of Alcohol: It is a physical change. The liquid is changed into gas