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2 years ago

In the first step in the life cycle of a star, it is called a:

Chemistry

1 answer:

KengaRu [80]2 years ago

7 0

Its called a protostar. This chemical change gives off a large amount of energy in the form of heat.

Brainiest plx

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Gather data: Four other pairs of elements in the same chemical family are listed below. List the number of valence electrons in

Iteru [2.4K]

Explanation:

Valence electrons is the number of electrons in the outermost shell of an atom. For the main group elements, the group number represents the number of valence electrons.

Beryllium

This belongs to the group 2 hence, it has valency of 2.

Nitrogen

This belongs to group 5, hence it has valency of 5.

Oxygen

This belongs to group 6, hence it has valency of 6.

Fluorine

This belongs to group 7, hence it has valency of 7.

Magnesium

This belongs to group 2, hence it has valency of 2.

Phosphorus

This belongs to group 5, hence it has valency of 5

Sulphur

This belongs to group 6, it has valency of 6

Chlorine

This belongs to group 7, it has valency of 7

6 0

3 years ago

Read 2 more answers

Devise a way to separate sand from a mixture of charcoal, sand, sugar, and water

madreJ [45]

A mixture of charcoal, sand, sugar, and water is a heterogeneous mixture. Sugar can easily dissolve in water. Slightly heating the mixture will ensure all of the sugar is dissolved in the water. The mixture then can be filtered to separate out sugar solution from sand and charcoal. The mixture of sand and charcoal is washed several times with water and filtered so that no traces of sugar solution remain in the mixture. To the mixture containing sand and charcoal, water is added. Charcoal being lighter floats on the surface of water, whereas sand being heavy sinks to the bottom. The charcoal floating can be removed manually. After all the charcoal is removed, the mixture of sand and water is again filtered and the sand collected on filter paper is dried. Therefore, by using the above process sand can be separated out from a mixture of charcoal, sand, sugar, and water.

5 0

3 years ago

6. Geologists in Egypt and Ethiopia are comparing rock samples from rocks

Tcecarenko [31]

Answer:

Both are different.

Explanation:

Both rocks are different from one another because both formed from different types of rocks. Rock A was formed from small pieces of rock while on the other hand, Rock B was formed from liquid rock so they both have different sources of rocks from which they were formed. Forming at the same time does not show that they are similar to each other, it is their source which decides that they are similar or different.

4 0

3 years ago

For every action there is an equal and opposite reaction is known as? *

wolverine [178]

Answer:

Newton's third law

3 0

3 years ago

Read 2 more answers

What is the mass percent of oxygen in sodium bicarbonate (NaHCO3)?

Alenkasestr [34]

The answer is 57.14%.

First we need to calculate molar mass of NaHCO3. Molar mass is mass of 1 mole of a substance. It is the sum of relative atomic masses, which are masses of atoms of the elements.

Relative atomic mass of Na is 22.99 g
Relative atomic mass of H is 1 g
Relative atomic mass of C is 12.01 g
Relative atomic mass of O is 16 g.

Molar mass of NaHCO3 is:
22.99 g + 1 g + 12.01 g + 3 · 16 g = 84 g

Now, mass of oxygen in NaHCO3 is:
3 · 16 g = 48 g

mass percent of oxygen in NaHCO3:
48 g ÷ 84 g · 100% = 57.14%

Therefore, the mass percent of oxygen in sodium bicarbonate is 57.14%.

8 0

3 years ago