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agasfer [191]
3 years ago
14

A scientific ________ must have a control, so that the variables that could affect the out come is reduced. A:experiment B:concl

usion. C:investigation. D:reasoning
Chemistry
1 answer:
Lostsunrise [7]3 years ago
4 0

Answer:

A.experiment

Explanation:

hope this helps

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Answer:John Dalton

Explanation:

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Which of those depend on mayfly nymphs. In other terms which animal eats mayfly nymphs?

I would say frogs
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2 years ago
identify each pair of compounds as constitutional isomers, stereoisomers, identical molecules, or other.
Lostsunrise [7]
I don’t know this answer
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In which reaction does the oxidation number of hydrogen change? In which reaction does the oxidation number of hydrogen change?
dedylja [7]

<u>Answer:</u> The correct answer is 2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)

<u>Explanation:</u>

Oxidation number is defined as the number which is given to an atom when it looses or gains electron. When an atom looses electron, it attains a positive oxidation state. When an atom gains electron, it attains a negative oxidation state.

Oxidation state of the atoms in their elemental state is considered as 0. Hydrogen is present as gaseous state.

For the given chemical reactions:

  • <u>Reaction 1:</u>  2HClO_4(aq.)+CaCO_3(s)\rightarrow Ca(ClO_4)_2(aq.)+H_2O(l)+CO_2 (g)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

  • <u>Reaction 2:</u>  CaO(s)+H_2O(l)\rightarrow Ca(OH)_2(s)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

  • <u>Reaction 3:</u>  HCl(aq.)+NaOH(aq.)\rightarrow NaCl(aq.)+H_2O(l)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

  • <u>Reaction 4:</u>  2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: 0

Thus, the oxidation state of hydrogen is changing.

  • <u>Reaction 5:</u>  SO_2(g)+H_2O(l)\rightarrow H_2SO_3(aq.)

Oxidation state of hydrogen on reactant side: +1

Oxidation state of hydrogen on product side: +1

Thus, the oxidation state of hydrogen is not changing.

Hence, the correct answer is 2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)

6 0
3 years ago
How many molecules of water are represented by the formula h2o
yaroslaw [1]

exactly 1 molecule of water is H2O just 1 is the answer

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