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Mariana [72]
3 years ago
14

Answer to this question?

Chemistry
2 answers:
bearhunter [10]3 years ago
6 0

Answer:

3rd one is the correct answer

Alja [10]3 years ago
3 0

Answer:

the third one I believe

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How much heat is required to decompose 25.5 grams of NaHCO3? 2NaHCO3(s) + 129 kJ 2Na2CO3(s) + H2O(
Vaselesa [24]
To determine the heat required in order to decompose a certain amount of a substance, we need information on the heat needed to decompose one mole of the substance. This value are readily available online and other sources. For this reaction, the heat needed is 129 kJ per 2 mol of NaHCO3. We calculate as follows:

129 KJ / 2 mol NaHCO3 (1 mol / 84.01 g ) (25.5 g NaHCO3 ) = 19.58 kJ of heat is needed.
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3 years ago
Which pair of elements can be used to determine the age of a fossil that is over one billion years old?
lakkis [162]

Answer:

Explanation:

There are some radioactive nuclides can be used to measure time on an archeological scale. One is the best example of this is radiocarbon dating. This process is based on the ratio of caebon-14 to carbon-12 in the atmosphere which is relatively constant.

The half time of C-14 5730 years  

Carbon-14 is a radioactive nucleus. It has a half-life of 5730 years.

All living tissues like plants and animal absorbed carbon-12 along with carbon-14 with same ratio of caebon-14 to carbon-12 in the atmosphere.

Carbon-14 dating is based on the ratio of carbon-14 to carbon-12 in the atmosphere which is relatively constant

3 0
3 years ago
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What kind of scientist would study the the first of a car running
iVinArrow [24]

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A physicist

Explanation:

hope this will help you

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Which medical condition(s) can prevent molecules from entering the cell?
kvasek [131]

Answer:

Explanation:

any type of spreading disease that kills

6 0
2 years ago
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A chemical reaction in which an uncombined element replaces an element that is part of a compound is called a
san4es73 [151]

Answer:

A chemical reaction in which an uncombined element replaces an element that is part of a compound is called a simple substitution reaction or simple displacement reaction.

Explanation:

A simple substitution reaction or simple displacement reaction, called single-displacement reaction, is a reaction in which an element of a compound is substituted by another element involved in the reaction. The starting materials are always pure elements and an aqueous compound. And a new pure aqueous compound and a different pure element are generated as products. The general form of a simple substitution reaction is:

AB + C → A +BC

where C and A are pure elements; C replaces A within compound AB to form a new co, placed CB and elementary A.

So, in a Single replacement reaction an uncombined element replaces an element.

<u><em>A chemical reaction in which an uncombined element replaces an element that is part of a compound is called a simple substitution reaction or simple displacement reaction.</em></u>

3 0
2 years ago
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