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Dahasolnce [82]

2 years ago

13

What are distinguishing features of animals? A) Generally an animal body exhibits a definite symmetry, form and shape. B) Growth

of the body occurs proportionately. C) Reserved food is glycogen. D) All of the above.

2 answers:

max2010maxim [7]2 years ago

5 0

Answer:

A

Explanation:

katrin2010 [14]2 years ago

5 0

Answer:

its D) all of the above

Explanation:

i learned this is like 6th grade

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Write the following number correct to 2 significant figures: 3644000<br><br> Hurry Plz NO TIME!!!

Nadusha1986 [10]

3644000 rounded to 2 significant figures is equivalent to 3.6

8 0

3 years ago

Read 2 more answers

1) How many molecules are there in 985 mL of nitrogen at 0.0° C and 1.00 x 10-6 mm Hg?

RSB [31]

Answer : The number of molecules present in nitrogen gas are, $3.48\times 10^{13}$

Explanation :

First we have to calculate the moles of nitrogen gas by using ideal gas equation.

$PV=nRT$

where,

P = Pressure of $N_2$ gas = $1.00\times 10^{-6}mmHg=1.32\times 10^{-9}atm$ (1 atm = 760 mmHg)

V = Volume of $N_2$ gas = 985 mL = 0.982 L (1 L = 1000 mL)

n = number of moles $N_2$ = ?

R = Gas constant = $0.0821L.atm/mol.K$

T = Temperature of $N_2$ gas = $0.0^oC=273+0.0=273K$

Now put all the given values in above equation, we get:

$(1.32\times 10^{-9}atm)\times 0.982L=n\times (0.0821L.atm/mol.K)\times 273K$

$n=5.78\times 10^{-11}mol$

Now we have to calculate the number of molecules present in nitrogen gas.

As we know that 1 mole of substance contains $6.022\times 10^{23}$ number of molecules.

As, 1 mole of $N_2$ gas contains $6.022\times 10^{23}$ number of molecules

So, $5.78\times 10^{-11}$ mole of $N_2$ gas contains $(5.78\times 10^{-11})\times (6.022\times 10^{23})=3.48\times 10^{13}$ number of molecules

Therefore, the number of molecules present in nitrogen gas are, $3.48\times 10^{13}$

8 0

3 years ago

Helppp meee Please

Fynjy0 [20]

Answer:

what do you need help with?

Explanation:

5 0

3 years ago

Why is a homogeneous mixture not considered a pure substance? Question 6 options: A pure substance can be separated by physical

krok68 [10]

1. Why is a homogeneous mixture not considered a pure substance?

<u><em>Answer:</em></u>

A pure substance can be separated by chemical means, while a mixture can be separated by physical means.

2. What is true if mass is conserved in a reaction?

<em><u>Answer:</u></em>

There are equal numbers of atoms on both sides.

3. <em>Methane reacts with oxygen then what are the products?</em>

<u><em>Answer:</em></u>

carbon dioxide and water

4. Which one of the following is not a homogeneous mixture?

<u><em>Answer:</em></u>

vegetable soup

5. The substance is not uniform in appearance and each part of the mixture contains a combination of different ingredients in different ratios.

<u><em>Answer:</em></u>

heterogeneous mixtures

6. If a solution is saturated, which of these is true?

<u><em>Answer:</em></u>

More solvent can be dissolved

7. Which of these substances are molecules?

<u><em>Answer:</em></u>

All compounds are molecules but not all molecules are compounds. Molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element. So correct option is 3 and 4.

8. What makes a solution a homogeneous mixture?

<u><em>Answer:</em></u>

It is uniform in composition.

9. When a solute is added to a solution, why does it remain homogeneous?

<em>Answer:</em>

The solute dissolves.

10. The chemical formula of glucose is C6H12O6, so it is classified as a(n)

<u><em>Answer:</em></u>

pure substance.

11. <em>How many chlorine (Cl) atoms would be in 4 molecules of salt (4 NaCl)?</em>

<u><em>Answer:</em></u>

4

12. <em>In a solution of salt and water, which component is the solute?</em>

<u><em>Answer:</em></u>

Salt

13. These substances are all H2O2, Li , NaCl , O2

<u><em>Answer:</em></u>

Pure Substances

14. If you have 5 grams of product after a chemical reaction, how many grams of reactants did you have at the start of the reaction?

<em>Answer:</em>

5

15. What is the difference between a compound and a mixture?

<u><em>Answer:</em></u>

A compound is a pure substance, but a mixture is not.

16. A firework exploding would be an example of a(n) ________.

<u><em>Answer:</em></u>

Exothermic reaction

17. If Lavoisier heated 100 grams of powdered mercuric oxide to produce 93 grams of liquid mercury, how much oxygen would be released?

Solution

2HgO ==> 2Hg + O2

Mass of HgO = 100 g

Molar mass of HgO = 216.59 g/mol

Moles = mass/molar mass = 0.46 moles

From balance chemcial equation

HgO : O2

2 = 1

0.46 = (1 × 0.46 ) ÷ 2 = 0.23 moles

mass of O2 = moles× molar mass = 0.23 × 32 = 7.36 g

18. Using the Law of Conservation of Matter, determine the number of grams of iron sulfide (FeS) that will be produced in this reaction.

<em><u>Solution</u></em>

12g Fe + 64g S → _____ g FeS

According to Law of Conservation of Matter, The total mass of reactant is equal to total mass of product , so the number of grams of iron sulfide (FeS) that will be produced in this reaction as follow.

12 + 64 = 76 g of FeS

Hope this Help.

3 0

3 years ago

Read 2 more answers

Give two examples of diffusion process in plants and animals.

lisabon 2012 [21]

answer:

in plants

Transport manufactured food from the leaves to others parts of the plant

Facilitates gaseous exchange through the stomata in the leaves to other parts of the plant

in animal

Exchange of respiratory gases across respiratory services

Excretion of nitrogenous waste in some unicellular organisms

Explanation:

Hope it benefit

3 0

3 years ago