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NISA [10]
3 years ago
12

A scientist is performing an experiment on a powder. Which of the following is a sign that a chemical change has definitely occu

rred during his experiment?
The powder catches on fire.
The powder releases bubbles.
The powder heats up.
The powder breaks apart into smaller particles.
Chemistry
1 answer:
n200080 [17]3 years ago
7 0
The powder catches fire. The rest of the choices pertains to physical changes on the powder. When the powder catches fire a chemical change happens. For example, if the powder is organic, carbon dioxide and water will result during the combustion. 
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4 0
3 years ago
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A gaseous substance turns directly into a solid. Which term describes this change?
UkoKoshka [18]

Answer:

deposition

Explanation:

Sublmation- solid transforming into a gas, skipping the liquid stage.

eveporation- a liquid transformimg into a gas

melting- a solid transforming into a liquid

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7 0
2 years ago
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Trava [24]
1) Chemical equation

Na2 SiO3 (s) + 8 HF (aq) ---> H2 Si F6 (aq) + 2 Na F (aq) + 3H2O (l)

It is balanced

2) Molar ratios

1 mol Na2 SiO3 : 8 mol HF.

3) Proportion

0.340 mol Na2 SiO3 * 8 mol HF / 1mol Na2SiO3 = 2.72 mol HF.

Answer: 2.72 mol HF

5 0
3 years ago
Which is a method that can be used to separate the components of a solution?
sashaice [31]

Answer:

Distillation

Explanation:

i hope this helps

4 0
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Fofino [41]

Answer:

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