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Ahat [919]
3 years ago
12

Which statements about gravity are true

Chemistry
1 answer:
Katen [24]3 years ago
7 0

Answer:

1.gravity helps us stay situated on earth without floating away  

3.gravity holds our galaxy together

4.multiplying the mass of an object by the acceleration due to gravity gives the weight of the object  

Explanation:

Man can float on moon. This is because the force of gravity on the moon is less than that on Earth. Thus gravity helps us not float away on Earth.  

All matter contains mass and has nothing to do with gravity. Option 2 is incorrect.

Gravity is a collection of billions of stars that are held together by gravity. Option 3 is correct.

Weight of the object is the product of the mass of an object and the acceleration due to gravity. Option 4 is correct.

Scientists launch space craft out of earths atmosphere  against Earth's gravity. Option 5 is incorrect.

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What causes water to increase in density?
murzikaleks [220]

Explanation:

temperature changes affect seawater density as water cools its density increases. As water cools H2O molecules pack more closely together because the molecules are vibrating less at low temperatures and take up less volume. The same number of water molecules in smaller volume results higher density

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One part of the cell theory states that all living things are made up of one or more cells. Scientists had to find ways to test
sergejj [24]

Answer:

A population or community research line can be carried out, wherever at a certain point in time, regardless of whether it is a cross-sectional study.

In addition, the people who would be the population to be studied or the object of study might or might not know the cause of the study (blind) while the researcher could be experimentally participatory.

Explanation:

They are prevalence studies, in which the presence of a health condition or state is determined in a well-defined population and in a determined time frame: one day, one week, a particular moment in life, even if it does not temporarily coincide in all the subjects (for example, the blood pressure figures at the time of entering the school or at the beginning of the holidays, the prevalence of diabetes in hospitalized patients on a given day, etc.).

They are like "photographs" of a state of affairs at a given moment. The simultaneous determination of what is understood by exposure and event does not allow defining causality.

5 0
2 years ago
A chemistry student needs to standardize a fresh solution of sodium hydroxide. He carefully weighs out 28.mg of oxalic acid H2C2
Nezavi [6.7K]

Answer:

  • The molarity of the student's sodium hydroxide solution is 0.0219 M

Explanation:

<u>1) Chemical reaction.</u>

a) Kind of reaction: neutralization

b) General form: acid + base → salt + water

c) Word equation:

  • sodium hydroxide + oxalic acid → sodium oxalate + water

d) Chemical equation:

  • NaOH + H₂C₂O₄ → Na₂C₂O₄ + H₂O

b) Balanced chemical equation:

  • 2NaOH + H₂C₂O₄ → Na₂C₂O₄ + 2H₂O

<u>2) Mole ratio</u>

  • 2mol Na OH : 1 mol H₂C₂O₄ :1 mol Na₂C₂O₄ : 2 mol H₂O

<u>3) Starting amount of oxalic acid</u>

  • mass = 28 mg = 0.028 g
  • molar mass = 90.03 g/mol
  • Convert mass in grams to number of moles, n:

        n = mass in grams / molar mass = 0.028 g / 90.03 g/mol =  0.000311 mol

<u>4) Titration</u>

  • Volume of base: 28.4 mL = 0.0248 liter
  • Concentration of base: x (unknwon)

  • Number of moles of acid: 2.52 mol (calculated above)
  • Proportion using the theoretical mole ratio (2mol Na OH : 1 mol H₂C₂O₄)

\frac{2}{1} =\frac{x}{2.52}\\ \\ \\x=0.000311(2)=0.000622

That means that there are 0.000622 moles of NaOH (solute)

<u>5) Molarity of NaOH solution</u>

  • M = n / V (liter) = 0.000622 mol / 0.0284 liter = 0.0219 M

That is the correct number using <em>three signficant figures</em>, such as the starting data are reported.

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3 years ago
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Na2SO3" represents sodium sulfite. What does the 4 mean in the formula 4Na2SO3? There are four atoms of sodium. There are four a
MArishka [77]

There are 4 atoms of sodium in the formula of sodium sulfite.

<h3 /><h3>Number of atoms at sodium</h3>

There are 4 atoms of sodium in the formula of sodium sulfite because 4 digit is placed before sodium which shows the number of sodium atom present in the molecule while on the other hand, 2 is placed in front of sulfur which tells us that 2 atoms of sulfur is used in the making of sodium sulfite.

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In this excerpt, Paine is attempting to convince the readers that we have righteous reasons to justify supporting the war. We should participate and take part in the war in order to defend ourselves and our country but avoid offensive war to gain financial benefits.

Learn more about war here: brainly.com/question/1174232

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How many moles of H2O are in 42.0 g H2O?
cricket20 [7]
(42/18.02)=2.3307mol H2O
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