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Over [174]
3 years ago
14

Please help me please

Chemistry
2 answers:
AnnZ [28]3 years ago
8 0

Answer:

20 is b and 21 is a.

Ludmilka [50]3 years ago
7 0

Answer:

b

Explanation:

i read this once and remember,trust me!

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What is the most appropriate unit of astronomical distance to represent the distance between an earth an orbiting space station
Reil [10]
Astronauts use "Astronomical Unit" to measure the distance between planets in our solar system "only". To measure long distances like between 2 galaxies, they use "light years". One Astronomical Unit = Average distance between sun and earth which is equal to 149.6 million kilometers. Ping me if you have any doubt.
4 0
2 years ago
A chemist carefully measures the amount of heat needed to raise the temperature of a 894.0g sample of a pure substance from to −
astraxan [27]

Answer:

C = 0.2349 J/ (g °C)

Explanation:

Mass, m = 894.0g

Initial Temperature = −5.8°C

Final Temperature =  17.5°C

Temperature change = 17.5°C - (−5.8°C) = 23.3

Heat, H = 4.90kJ = 4900 J

Specific heat capacit, C = ?

The relationship between these quantities is given by the equation;

H = mCΔT

C = H / mΔT

C = 4900 / (894)(23.3)

C = 0.2349 J/ (g °C)

4 0
2 years ago
Why was it important to establish the Clean Air Act?
deff fn [24]

Answer:

C.

Explanation:

The Clean Air Act was enacted in 1973 and brought to action in 1990. The act was passed to supervise air emissions to ensure clean air and atmosphere for people. The act was passed in the wake of premature deaths of hundred of thousands people. The act works with NAAQS to ensure safe and clean air for the safety of public health.

<u>From the given options the correct one is C. The Clean Air Act supervises the activities which emits air and any activities that is found to pollute the air will be labelled as illegal</u>.

Therefore, option C is correct.

5 0
2 years ago
Continental crust is younger than oceanic crust.
tankabanditka [31]

Answer:

The answer is true.

Explanation:

Hello! Let's solve this!

The answer is true.

When a crust undergoes great tension, a crack opens and the oceanic crust begins to form. As the crack enlarges, the continent is splitting. Thus an oceanic crust forms. So the oceanic crust is younger than the earth's crust.

7 0
3 years ago
Read 2 more answers
Why would a pregnant mother need more calcium than a woman her age that is not pregnant?​
inessss [21]

Besides building teeth and bones, calcium also keeps your blood and muscles moving and helps your nerves send messages from your brain to the rest of your body. Your body can't make calcium, so you need to get it from food or supplements. While you're pregnant, try to get at least 1,000 mg of calcium every day.

5 0
3 years ago
Read 2 more answers
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