Explanation

The stratospheric ozone layer is Earth's “sunscreen”  protecting living things from too much ultraviolet radiation from the sun.

Oxygen layer in the atmosphere

Ozone protects us from the harmful ultraviolet radiation of the sun.

Ozone formula: O3

The ozone layer lies approximately 15-40 kilometers (10-25 miles) above the Earth's surface, in the stratosphere.

The ozone layer is depleting: Air pollution

ND17-7-2023

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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 

Explanation

Desalination – is a process by which saline water (generally sea water) is converted to fresh water.

The most common desalination processes are distillation and reverse osmosis.

Explanation

Refracting telescope is a type of optical telescope that uses a lens as its objective to form an image.

Refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses. 

Explanation

A 100-gram serving of cooked beef provides 250 calories, 35 grams of protein, and 10 grams of fat (5.2 grams which is healthier monounsaturated fat)

Explanation

• The bacterial disease is: Leprosy
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• Hansen's disease also known as leprosy
• Hansen's disease is an infection caused by slow-growing bacteria called Mycobacterium leprae.
• It can affect the nerves, skin, eyes, and lining of the nose (nasal mucosa).
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• the Brucellosis bacterial disease has recently hit China affecting over 3000 people
• Hepatitis is not a bacterial disease
  

Explanation

Explanation

Pertussis vaccine is commonly given in the following two forms:

1.      Whole-cell vaccine

2.      Acellular vaccine 

Explanation

Agrostology, the branch of botany concerned with the study of grasses, especially their classification.

Agrostology means مطالعہ گھاس

Explanation

Smelting uses heat and a chemical-reducing agent to decompose the ore,

driving off other elements as gases or slag

and leaving the metal base behind.

Smelting is a method used in the extraction of metals that involves heating the metal oxide produced from roasting with a reducing agent, such as carbon, to obtain pure metal.

ND-21-5-2023