Witch event signals the birth of a star

Answer:

21: True

22: False

23: True

24: False

25: False

26: True

27: True

28: False

30: True

Explanation: Hope this is helpful :)

Answer:

yes, A double replacement reaction has two compounds as reactants.

hence it's true.......

Answer:

it's true...

Explanation:

Answer:

use wire nettings

Explanation:

and cages

Answer:

some animals exhibit structures that are no longer used for any purpose

Explanation:

Vestigial structures are defined as the the organs which are no longer used for any purpose.

Vestigial structures provide evidences of common ancestors as they shows how organisms changed or evolved in the use of these structures. for example: human appendix which is no longer functional in human body but as per Darwin's theory of evolution it was once used by our herbivorous ancestors to protect good bacteria in the gut.

Hence, the correct answer is "some animals exhibit structures that are no longer used for any purpose".

Answer:

The rib and loin, because of their palatability and diversity in how they can be used--especially on the market.

Explanation:

Answer:

Colloids are mixtures in which one or more substances are dispersed as relatively large solid particles or liquid droplets throughout a solid, liquid, or gaseous medium.

Answer:

Colloids are mixtures in which one or more substances are dispersed as relatively large solid particles or liquid droplets throughout a solid, liquid, or gaseous medium.

Explanation:

I got the answer first

Explanation:

Pure water does not conduct electricity. This is because pure water do not contain any salts. Pure water can conduct electricity when common salt is added to it, as salt solution is conducting in nature.

Answer:

Explanation:

Cellular respiration does not depend on light...  Some plants may go into a form of hibernation during winter when the amount of light during the day is less.  The reduction of plant growth and activity would reduce the need for the energy produced by cellular respiration.

Answer:

3) All the animals and plants in a desert

4) Species becoming extinct

Answer:

It has shone a light on our (I live in the u.s.) raciest past and now more then ever people are listening to science, even more so depending on it!

Answer: There are 113 moles of O in 12.6 moles of [tex]Fe(NO_3)_3[/tex]

Explanation:

Given : moles of [tex]Fe(NO_3)_3[/tex] = 113.4

To find : moles of O = ?

1 mole of [tex]Fe(NO_3)_3[/tex] contains = 9 moles of O atoms

Thus 12.6 mole of [tex]Fe(NO_3)_3[/tex] contains = [tex]\frac{9}{1}\times 12.6=113.4[/tex] moles of O atoms

Thus there are 113 moles of O in 12.6 moles of [tex]Fe(NO_3)_3[/tex]

Answer:

i believe it is a

Explanation:

The reason is :a.They can gain more food for their offspring

Animals tend to protect their territory because they don't want  intruders to invade their territory.

Animals majorly protect their territory in order to protect their foods from been eating by intruders as this will enables their offerings to have enough foods to eat.

They as well guard  their territory in order to prevent intruders from invading the place they have prepare as their mating place.

Inconclusion  The reason why some animals defend  their territory after they have mated

and reproduced is :a.They can gain more food for their offspring

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Answer:

Cellular respiration uses energy in glucose to make ATP. Aerobic (''oxygen-using”) respiration occurs in three stages: glycolysis, the Krebs cycle, and electron transport. In glycolysis, glucose is split into two molecules of pyruvate. This results in a net gain of two ATP molecules.

Answer:

Explanation:

The insects have been defined as the most successful arthropods. There are far more species in the class Insecta than in any other group of animals. The insects are the only invertebrates with wings.

The insects play a very important role in the web of the life in every environment. Their jobs include pollinating flowering plants, since it is the source of food for insectivorous animals and it assist in the decomposition of plants and animals.

The two different methods which help to identify the species of the insects from the eggs on human remains are by using a small paint brush dipped in water and the other way is by using the forceps.

The study of insects and their life cycle are found to be important for the forensic entomologist. This is because it could set a timeline on when the crime is happened. The life cycle of a blowfly starts as an egg and then goes to be maggots.

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Answer:

a) the tendency to form hard, brittle crystals.

Explanation:

Metallic bonding occurs between metals; metals are excellent conductors of electricity, are malleable (can be hammered into thin sheets) and have luster (are shiny). Brittleness is indicative of an ionic bond or ionic compound.

Answer:

true

Explanation:

one reason is because plants need sunlight and water because it is their source of food

Answer:

hope this helps

Explanation:

Photosynthesis

Photosynthesis

Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's metabolic activities. This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water – hence the name photosynthesis, from the Greek phos, "light", and sunthesis "putting together". In most cases, oxygen is also released as a waste product. Most plants, algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth.

Answer:

79'420J

Explanation:

We know mass 250g and

∆T=98°C -22°C

=76°C

The specific heat capacity for water is 4,18Zj/g°C

THEREFORE

∆H=250g•14,8j/g°C •76°C

=79'420J

Answer:

A. 650 g

Explanation:

The equation of the reaction is given as;

2 HgO(s) --> 2Hg(s)  + O2(l)

From the reaction;

2 mol of HgO produces 1 mol of O2

x mol of HgO would produce 1.50 mol of O2

2 = 1

x = 1.5

Solving for x;

x = 1.5 * 2 / 1 = 3 mol

Converting to mass;

Mass = Number of moles * Molar mass

Mass = 3 mol  * 216.59 g/mol

Mass = 649.77 g ≈ 650. g

Correct option is ;

A. 650 g

Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, all amounts are the same. The correct option is option D.

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance. It measure the number of elementary entities of a given substance that are present in a given sample. There are so many formula for calculating mole. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.

Calculating the amount of a chemical in grams from moles is among the most often chemistry computations. You will employ the mole ratio of reactants to reagents when balancing equations.

Therefore, all amounts are the same. The correct option is option D.

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Answer:

a

Explanation:

a because a

Answer:

Cold fronts can produce dramatic changes in the weather.  

Explanation: They move fast, up to twice as fast as a warm front. As a cold front moves into an area, the heavier (more dense) cool air pushes under the lighter (less dense) warm air, causing it to rise up into the troposphere.

Answer:

the person above is correct

Explanation:

just to confirm it

hope th8s helps!

have a good day :)

Explanation:

A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7.

Answer:

i think the answer is f as metals are malleable and ductile

Answer:

F

Explanation: Most metals carry the trait that they are malleable and ductile.

Answer:

5. The mass of Na₂CO₃, that will produce 5 g of CO₂ is approximately 12.04 grams of Na₂CO₃

6. The mass of nitrogen gas (N₂) that will react completely with 150 g of hydrogen (H₂) in the production of NH₃ is 693.[tex]\overline{3168}[/tex] grams of N₂

Explanation:

5. The given equation for the formation of carbon dioxide (CO₂) from sodium bicarbonate (Na₂CO₃)  is presented as follows;

(Na₂CO₃) + 2HCl → 2NaCl + CO₂ + H₂O

One mole (105.99 g) of Na₂CO₃ produces 1 mole (44.01 g) of CO₂

The mass, 'x' g of Na₂CO₃, that will produce 5 g of CO₂ is given by the law of definite proportions as follows;

[tex]\dfrac{x \ g}{105.99 \ g} = \dfrac{5 \ g}{44.01 \ g}[/tex]

[tex]\therefore {x \ g} = \dfrac{5 \ g}{44.01 \ g} \times 105.99 \ g \approx 12.04 \ g[/tex]

The mass of Na₂CO₃, that will produce 5 g of CO₂, x ≈ 12.04 g

6. The chemical equation for the reaction is presented as follows;

N₂ + 3H₂ → 2NH₃

Therefore, one mole (28.01 g) of nitrogen gas, (N₂), reacts with three moles (3 × 2.02 g) of hydrogen gas (H₂) to produce 2 moles of ammonia (NH₃)

The mass 'x' grams of nitrogen gas (N₂) that will react completely with150 g of hydrogen (H₂) in the production of NH₃ is given as follows;

[tex]\dfrac{x \ g}{28 .01 \ g} = \dfrac{150 \ g}{3 \times 2.02 \ g} = \dfrac{150 \ g}{6.06 \ g}[/tex]

[tex]\therefore \ x \ g= \dfrac{150 \ g}{6.06 \ g} \times 28.01 \ g = 693.\overline {3168} \ g[/tex]

The mass of nitrogen gas (N₂) that will react completely with 150 g of hydrogen (H₂) in the production of NH₃, x = 693.[tex]\overline{3168}[/tex] grams