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2 years ago

What’s the star made up of challenge?

Chemistry

1 answer:

Crank2 years ago

4 0

Answer:

Stars are made of very hot gas. This gas is mostly hydrogen and helium, which are the two lightest elements. Stars shine by burning hydrogen into helium in their cores, and later in their lives create heavier elements.Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores.

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How does acid rain happen? (Use the term Sulfur Dioxide) PLS HALP

mafiozo [28]

Acid rain<span> is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as </span>acid rain<span>.</span>

6 0

3 years ago

The half life of a radioactive element is 2 million years. a mass of rock originally contained 200g of this element. how many gr

julia-pushkina [17]

Every 2 million years the amount is halved
0 million = 200g
2 million = 200g/2 = 100g
4 million = 100g/2 = 50g

8 0

2 years ago

The conversation of cyclopropane to propene in the gas phase is a first order reaction with a rate constant of 6.7x10-⁴s-¹. a) i

Rus_ich [418]

Answer: a) The concentration after 8.8min is 0.17 M

b) Time taken for the concentration of cyclopropane to decrease from 0.25M to 0.15M is 687 seconds.

Explanation:

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant

t = age of sample

a = let initial amount of the reactant

a - x = amount left after decay process

a) concentration after 8.8 min:

$8.8\times 60s=\frac{2.303}{6.7\times 10^{-4}s^{-1}}\log\frac{0.25}{a-x}$

$\log\frac{0.25}{a-x}=0.15$

$\frac{0.25}{a-x}=1.41$

$(a-x)=0.17M$

b) for concentration to decrease from 0.25M to 0.15M

$t=\frac{2.303}{6.7\times 10^{-4}s^{-1}}\log\frac{0.25}{0.15}\\\\t=\frac{2.303}{6.7\times 10^{-4}s^{-1}}\times 0.20$

$t=687s$

7 0

3 years ago

Which compound contains both covalent and ionic bonds? <br> a. NCl3 b. NaF c. HCN d. NH4OH

Marina86 [1]

<h2> $NH_4OH$ contains both covalent and ionic bonds.</h2>

Explanation:

A covalent bond is formed when an element shares its valence electron with another element. This bond is formed between two non metals.

An ionic bond is formed when an element completely transfers its valence electron to another element. The element which donates the electron is known as electropositive element or the metal and the element which accepts the electrons is known as electronegative element or non metal.

a. $NCl_3$ contain covalent bonds as they are made up of non metals only.

b. $NaF$ contain ionic bonds as they are made up of sodium metal and fluorine non metal.

c. $HCN$ contain covalent bonds as they are made up of non metals only.

d. $NH_4OH$ contain ionic bonds between $NH_4$ and $OH$ and covalent between N and H in $NH_4^+$

Learn more about ionic and covalent bonds

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8 0

2 years ago

Can two organisms belong to the same family but different classes? Explain.

slega [8]

This information is correct. This is because the order of classification is domain, kingdom, phylum, class, order, family, genus, species. Since class comes before family, the two organisms could be in the same class, but then when you specify further, they could be in different families.

7 0

2 years ago