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Shtirlitz [24]
3 years ago
14

Which of these describes a physical change? Choose the correct answer. You may only choose one.

Chemistry
1 answer:
Molodets [167]3 years ago
5 0

Answer:

A. Wood logs are burned in a fire

Explanation:

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6. Macromolecules represent which level of organization in the body?
hodyreva [135]

Answer:

Chemical

Explanation:

Macromolecules are part of the chemical components of cells. For example, DNA, proteins, and lipids.

Cells of similar types/function form tissues. Different types of tissues interact together to form organs. Organs form a common function.

6 0
3 years ago
1. Find the masses of the following amounts.
In-s [12.5K]

The mass of 2.15 mol of hydrogen sulphide (H₂S) will be 73.272 gm and the mass of  3.95 × 10⁻³ mol of lead(II) iodide, (PbI₂) will be 1.82 gm

<h3>What is Mole ?</h3>

A mole is a very important unit of measurement that chemists use.

A mole of something means you have 6.023 x 10 ²³ of that thing.

  • For 2.15 mol of hydrogen sulphide (H₂S) :

1 mole hydrogen sulphide (H₂S) = 34.08088 grams

Therefore,

2.15 mol of hydrogen sulphide (H₂S) = 34.08088 grams x 2.15 mol

                                                              = 73.272 gm

  • For 3.95 × 10⁻³ mol of lead(II) iodide, (PbI₂) ;

1 mol of lead(II) iodide, (PbI₂) = 461.00894 grams

Therefore,

3.95 × 10⁻³ mol of lead(II) iodide, (PbI₂) = 461.00894 grams x 3.95 × 10⁻³ mol

                                                                  = 1.82 gm

Hence,The mass of 2.15 mol of hydrogen sulphide (H₂S) will be 73.272 gm and the mass of  3.95 × 10⁻³ mol of lead(II) iodide, (PbI₂) will be 1.82 gm

Learn more about mole here ;

brainly.com/question/21323029

#SPJ1

7 0
2 years ago
1.2 L sample of gas is determined to contain 0.5 moles of nitrogen. At the same temperature and pressure, how many moles of gas
hram777 [196]

A 20 L sample of the gas contains 8.3 mol N₂.

According to <em>Avogadro’s Law,</em> if <em>p</em> and <em>T</em> are constant

<em>V</em>₂/<em>V</em>₁ = <em>n</em>₂/<em>n</em>₁

<em>n</em>₂ = <em>n</em>₁ × <em>V</em>₂/<em>V</em>₁

___________

<em>n</em>₁ = 0.5 mol; <em>V</em>₁ = 1.2 L

<em>n</em>₂ = ?;           <em>V</em>₂ = 20 L

∴<em>n</em>₂ = 0.5 mol × (20 L/1.2 L) = 8.3 mol

4 0
3 years ago
A sample of phosphorus-32 has a half-life of 14.28 days. If 55 g of this radioisotope remain unchanged after approximately 57 da
Flura [38]
55= No (1/2)^55/57
55= No (1/2)^3.9
55= No (1/2)^4
55= No (1/16)
No= 880 g
7 0
3 years ago
Read 2 more answers
What four factors influence the rate of a homogeneous reaction.
Anika [276]
1) concentration or partial pressure of species
involved. 2) temperature • 3) presence of catalyst
4) nature of reactants.
5 0
2 years ago
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