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leonid [27]
3 years ago
10

.1. Which step in a scientific investigation would a scientist usually do before she performs an experiment?

Chemistry
2 answers:
faust18 [17]3 years ago
8 0
Form a hypothesis is right answer.
Hope it helps 
kherson [118]3 years ago
4 0
She would form a hypothesis and then conduct research
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Which of the following choices are types of energy?
Alika [10]
Kinetic and nuclear are energies
7 0
3 years ago
Read 2 more answers
If air is 80 percent nitrogen and 20 percent oxygen by volume what is density
Evgen [1.6K]
1 mol of any gas or mix of gases at STP conditions will have a volume of 22.4 L. Since the problem doesn’t said what are the conditions I will asume that are STP condition and the volume of one mole of the mix will have a volume of 22.4 L.

You may know that density is
D=m/v

In one mole of air I will have 80% of Nitrogen (N2) and 20% oxygen (O2).

So the mass of one mole of air will be

14 x2x0.80+16x2x0.20 = 22.4 g + 6.4 g = 28.8 g

D= 28.8/22.4 = 1.28 g/L

Of course if the temperature is higher the density will be smaller because the volume of one mole will be bigger and viceversa if the temperature decrease. Also if the pressure is different than one atm the volume of a mol will change.
5 0
3 years ago
A solution contains 0.775 g Ca2 0.775 g Ca2 in enough water to make a 1925 mL1925 mL solution. What is the milliequivalents of C
Romashka [77]

Answer: There will be 0.00002 meq per Liter of the solution.

Explanation:

Normality is defined as the umber of gram equivalents dissolved per liter of the solution.

Normality=\frac{\text{no of gram equivalents} \times 1000}{\text{Volume in ml}}

Normality=\frac{\text{given mass}\times 1000}{\text {Equivalent mass}\times {\text{Volume in ml}}}

Equivalent weight is calculated by dividing the molecular weight by n factor.   {\text{Equivalent weight}}=\frac{\text{Molecular weight}}{n}

n= charge for charged species  , For Ca^{2+} , n =2

{\text{Equivalent weight}}=\frac{40}{2}=20g

\text{no of gram equivalents}=\frac{0.775g}{20g/mol}=0.04gramequivalents

Normality=\frac{0.04\times 1000}{1925}=0.02eq/L=0.00002meq/L

Thus there will be 0.00002 meq per Liter of the solution.

3 0
4 years ago
Express your answer as a balanced chemical equation. Identify all of the phases in your answer.
SpyIntel [72]

Answer:

H₂S(aq)+ 2 LiOH(aq) → Li₂S(aq) + 2 H₂O(l)

6 HI(aq) + 2 Al(s) → 2 AlI₃(aq) + 3 H₂(g)

2 H₂SO₄(aq) + TiO₂(s) → Ti(SO₄)₂(aq) + 2 H₂O(l)

H₂CO₃(aq) + 2 LiOH(aq) → Li₂CO₃(aq) + 2 H₂O(l)

Explanation:

H₂S(aq)+ 2 LiOH(aq) → Li₂S(aq) + 2 H₂O(l)

This is a neutralization reaction. The products are salt and water.

6 HI(aq) + 2 Al(s) → 2 AlI₃(aq) + 3 H₂(g)

This is a single displacement reaction.

2 H₂SO₄(aq) + TiO₂(s) → Ti(SO₄)₂(aq) + 2 H₂O(l)

This is a neutralization reaction. The products are salt and water.

H₂CO₃(aq) + 2 LiOH(aq) → Li₂CO₃(aq) + 2 H₂O(l)

This is a neutralization reaction. The products are salt and water.

5 0
3 years ago
Which isotope is used to date ancient artifacts such as fossils?
RideAnS [48]

Scientists use carbon-14 to date ancient fossils.

Plants and animals absorb carbon-14 produced by cosmic rays. The ratio of C-14 to C-12 is constant when they are alive.

When they die, the C-14 decays to C-12, and the ratio changes.

Carbon-14 has a half-life of 5730 years. Thus, the object loses half its C-14 every 5730 years.

Scientists can use the C-14 to C-12 ratio to date fossils up to 70 000 years old.

6 0
3 years ago
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