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zzz [600]
3 years ago
13

Scientific knowledge results from the interaction of scientists who are investigating natural phenomena. Which of these BEST des

cribes how a scientific explanation becomes widely accepted?
Group of answer choices

DNA is not necessary for an organism to reproduce.

Organisms create their own DNA sequence that is not like their parents.

. DNA contains genes that hold specific traits for an organism.

A. DNA is an exact copy from parent to offspring.
Chemistry
1 answer:
seraphim [82]3 years ago
6 0

Answer:

5ywhxhghghghfhffgffgffg

Explanation:

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A hard-water solution contains 4.8 g of calcium chloride. How much sodium phosphate in grams should be added to the solution to
alexgriva [62]

Answer:

4.7 g

Explanation:

The reaction that takes place is:

  • 3CaCl₂(aq) + 2Na₃PO₄(aq) → Ca₃(PO₄)₂(s) + 6NaCl(aq)

First we <u>convert 4.8 g of CaCl₂ into moles</u>, using its <em>molar mass:</em>

  • 4.8 g ÷ 110.98 g/mol = 0.0432 mol CaCl₂

Then we<u> convert CaCl₂ moles into Na₃PO₄ moles</u>, using the <em>stochiometric coefficients of the balanced reaction</em>:

  • 0.0432 mol CaCl₂ * \frac{2molNa_3PO_4}{3molCaCl_2} = 0.0288 mol Na₃PO₄

Finally we <u>convert 0.0288 moles of Na₃PO₄ into grams</u>, using it<em>s molar mass</em>:

  • 0.0288 mol Na₃PO₄ * 164 g/mol = 4.7 g

8 0
3 years ago
For a solution equimolar in HCN and NaCN, which statement is false? a. [H+] is larger than it would be if only the HCN were in s
balandron [24]

Answer:

option  (d) is false.

Explanation:

Acid dissociation equilibrium of HCN is represented as-

 HCN\rightleftharpoons H^{+}+CN^{-}

Acid dissociation constant, K_{a}, is represented as-

K_{a}=\frac{[H^{+}][CN^{-}]}{[HCN]}

where species inside third bracket represents equilibrium concentrations of respective species

So, evidently, presence of excess CN^{-} (or NaCN) in solution will combine with H^{+} to produce HCN. Hence H^{+} will be larger that it would be if only the HCN solution were present.

According to Le-chatlier principle, addition of HCN will shift equilibrium towards right and addition of NaCN will shift equilibrium towards left to keep constant K_{a} value at a particular temperature.

NaOH gives acid-base reaction with HCN to produce NaCN and water. So, addition of NaOH will increase concentration of CN^{-} and decrease concentration of HCN

6 0
3 years ago
The reduced vapor pressure at high altitudes causes a liquid to boil at a temperature.
irinina [24]
<span>At higher altitudes (and thus lower atmospheric pressures), water boils at a lower temperature. This is because the lack of vapor pressure at that altitude doesn't constrain the speed of the molecules with barometric pressure. Therefore, the water begins boiling at a lower temperature. This is often a disadvantage because even if the water is boiling, it won't be hot enough for meals (which is why heat and temperature are distinct). That's why we have pressure cookers, which manage to keep a stable boiling point.
Did that help?</span>
5 0
3 years ago
Read 2 more answers
Any mechanical device which is used to help people do work is a <br> .a0
KIM [24]
Any mechanical device which is used to help people is a (machine)
the answer is machine
3 0
3 years ago
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What happens to elements when they combine together chemically ?
lara [203]

Answer:

When two distinct elements are chemically combined—i.e., chemical bonds form between their atoms—the result is called a chemical compound. Most elements on Earth bond with other elements to form chemical compounds, such as sodium (Na) and Chloride (Cl), which combine to form table salt (NaCl).

7 0
3 years ago
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