An atom of an element contains 12 protons, 12 neutrons, and 12 electrons. This element is in Group A) 1 B) 2 C) 6 D) 18

Answer:

The composition of a pure substance is always the same, regardless of the source, but the composition of a mixture can vary.

Mixtures can be separated into their components by physical changes; some pure substances can be separated into components by chemical change.

Explanation:

A chemically pure substance has a well defined and constant composition. The composition of a chemically pure substance remains the same irrespective of its source. Also, the components of a chemically pure substance may be separated by chemical changes.

Mixtures have a variable composition depending on their  respective sources. The composition of a mixture varies with the source of the mixture and mixtures are separated by physical processes.

Answer:

Balanced equation:

CaCO3 (s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)

1mol CaCO3 will react with 2 mol HCl

Mol HCl in 32.8mL of 1.25M solution = 32.8mL / 1000mL/L * 1.25mol /L = 0.041 mol HCl

This will react with 0.041/2 = 0.0205 mol CaCO3

Molar mass CaCO3 = 100g/mol

Mass of CaCO3 reacted = 0.0205mol *100g/mol = 2.05g CaCO3.

Grams are the unit of weight or mass that depicts the quantity of a substance. The mass of calcium carbonate reacted is 2.05 gm.

Mass is the product of the moles of the compound and its molar mass, it is given in grams.

The balanced chemical reaction is given as:

[tex]\rm CaCO_{3} (s) + 2HCl(aq) \rightarrow CaCl_{2}(aq) + CO_{2}(g) + H_{2}O(l)[/tex]

From the reaction, 1 mole of calcium carbonate reacts with 2 moles of hydrochloric acid.

Moles of hydrochloric acid is calculated as:

[tex]\begin{aligned} \rm n &= \rm Molarity \times Volume (L)\\\\&= 0.0328 \times 1.25\\\\&= 0.041\;\rm mol\end{aligned}[/tex]

Now, the moles of calcium carbonate it will react with will be 0.0205 moles.

Mass of calcium carbonate is calculated as:

[tex]\begin{aligned} \rm mass &= \rm molar\; mass \times moles\\\\&= 0.0205 \times 100\\\\&= 2.05 \; \rm g\end{aligned}[/tex]

Therefore, 2.05 gm of calcium carbonate is needed to react with 15.2 gm of hydrochloric acid.

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Answer:

(d) soap.

Explanation:

A soap is obtained by alkaline hydrolysis of a fat to yield the soap and glycerol. This process is known as saponification.

A soap solution is usually basic. Since phenolphthalein turns pink in an alkaline solution, then when phenolphthalein is added to a soap solution, the solution soon turns pink because it is alkaline in nature.

As a matter of fact, a soap sometimes has almost the pH of baking soda!

Explanation:

The reaction rate decreases with a decrease in temperature. Catalysts can lower the activation energy and increase the reaction rate without being consumed in the reaction. Differences in the inherent structures of reactants can lead to differences in reaction rates.

Answer:

18x3=54 gram

Explanation:

When you express molecular mass (in case of molecule)/atomic mass(in case of atom) in gram it will be equivalent to one mole. For example:

12 gram Carbon atom = 1 mole of Carbon atom = N number of Carbon atom

16 gram Oxygen atom= 1 mole of Oxygen atom = N number of Oxygen atom

32 gram Oxygen molecule (O2) = 1 mole of Oxygen molecule (O2) = N number of Oxygen molecule (O2)

similarly 1 mole of water is equivalent to molecular mass of water x 3 that is 18x3=54 gram. It would constitute 3N molecules of water.

N: Avogadro's number : 6.022140857 × 10^23

Answer:

Moles of sodium = 15.0⋅g22.99⋅g⋅mol−1 = 0.652⋅mol . Given the stoichiometry of the reaction, clearly 0.652⋅mol sodium hydroxide will result.

Explanation:

please mark me

From the balanced chemical equation of the reaction, it is clear that, 2 moles or 46 g of sodium metal produce 2 moles of NaOH. Then, 15 g or 0.65 moles of Na metal will give 0.65 moles or 26 g of NaOH.

The balanced chemical equation of a reaction represent the correct stoichiometry of all the reactants and products in the reaction. It is balanced as per the law of conservation of masses. Hence, the total mass of the reactant side is equal to the total mass of the product side.

From the given balanced chemical equation of the reaction, it is clear that, 2 moles of Na reacts with one mole of water to give two moles of NaOH and one mole of hydrogen gas.

Atomic mass of Na = 23 g/mol

no.of moles in 15 g = 15 g /23g/mol = 0.65 moles.

2 moles of Na gives 2 moles of NaOH. Then, 0.65 moles of Na will given 0.65 moles of NaOH.

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Answer:

The nuclear decay of radioactive elements is a process that is a useful tool for determining the absolute age of fossils and rocks. It is used as a clock, in which daughter elements or isotopes converted from parent isotopes by decaying at a particular time.

Radioactive decay rates are constant and do not change over time. It is measured in half-life. A half-life is a time it takes half of a parent isotope to decay and converted into a stable daughter isotope. How many parent isotopes and daughter isotopes present in the fossil or their abundance can help in determining the age of fossil or rock.

Answer:

The correct answer is -

3. Butyne

4. Pentene

Explanation:

The names of such organic compounds are classified on the number of the carbon atoms and based on a number these prefixes are attached -

Meth - one carbon

Eth - two carbons

Prop - three carbons

But - four carbons

Pent - five carbons, and so on

The bonds can be identified by names of an organic compound by their suffixes -

- ane = single bond

- ene = double bond

-yne = triple bond

Thus, for question 3, carbon numbers are 4 and triple bond so Butyne, and similarly for question 4, 5 carbon atoms and double bond so Pentene.

Answer:

D. Two Plates are colliding.

Answer:

D

Explanation:

The ring of fire has very large amount of plate collision so it cannot be B.

It can't be A either because the ring of fire has nothing to do with radioactive element decay.

The two main things with the ring of fire is the fact that there are a lot of volcanos and earthquakes, so it cannot be C.

Since the ring of fire has so many collisions of plates, and none of the other answers are correct, the answer is D.

Hope this helps!

Answer:

[tex]1 \: mole = 6.02 \times {10}^{23} \: atoms \\ 6.5 \: moles = (6.5 \times {6.02 \times 10}^{23} ) \: atoms \\ = 3.913 \times {10}^{24} \: atoms[/tex]

Answer:

D. The Sun

Explanation:

The Sun does not affect global wind belts.

Land breeze does not affect global wind belts whereas other factors such as air pressure, Coriolis effect and the sun affected global wind patterns.

Unequal heating of the Earth's surface forms large global wind patterns. Those area which are near the equator, the sun warm air and this warm air rises at the equator and moves toward the poles. At the poles, the cooler air sinks and moves back toward the equator.

So we can conclude that land breeze does not affect but sun creates affect on the global wind pattern.

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Answer:

The correct answer is - Mosquitoes transmit the virus as parasites which feed on the blood of host organisms and inject the virus during feeding.

Explanation:

According to the CDC, the seasonal West Nile virus is caused by the mosquitoes of freshwater transmit this disease to humans and others. These mosquitoes are feed on the birds and pick these viruses.

These viruses stick on mosquitoes and when they feed on the blood of humans they transmit these viruses by injecting viruses into the blood of humans.

Answer:

[tex]187.[/tex]

Explanation:

[tex]7.5 \div 0.30 = 25[/tex]

[tex]7.5 \times 25 = 187.5[/tex]

Answer:

B - To increase the rate of the reaction

Explanation:

Catalysts speed up the reaction without being reactants or products, so aren't used up in the reaction.

Answer:

O Al + Mg(NO3)2 -->

Explanation:

Answer:

Look down below

Explanation:

Environmmetal impacts that coal can cause is Sulfur dioxide (SO2), which contributes to acid rain and respiratory illness.

AND.....

Nitrogen oxides (NOx), which contribute to smog and respiratory illnesses. Particulates, which contribute to smog, haze, and respiratory illnesses and lung disease

Answer:

10.

Explanation:

We need 10 question to separate ten arthropods into different branches because each arthropod belongs to separate branch and each branch needs explanation. Phylum Arthropoda is considered as the largest phylum in the animal world, and insects form the largest class within this phylum due to its highest number of individual or organisms. Each arthropods are different from one another so they needs more questions to separate them from each other.

Answer:

[tex]\boxed {\boxed {\sf 1290 \ g \ PI_3}}[/tex]

Explanation:

We want to convert from moles to grams, so we must use the molar mass.

The molar mass is the mass of 1 mole of a substance. It is the same as the atomic masses on the Periodic Table, but the units are grams per mole (g/mol) instead of atomic mass units (amu).

We are given the compound PI₃ or phosphorus triiodide. Look up the molar masses of the individual elements.

Note that there is a subscript of 3 after the I in the formula. This means there are 3 moles of iodine in 1 mole of the compound PI₃. We should multiply iodine's molar mass by 3, then add phosphorus's molar mass.

Use the molar mass as a ratio.

[tex]\frac {411.687262 \ g \ PI_3}{ 1 \ mol \ PI_3}[/tex]

We want to convert 3.14 moles to grams, so we multiply by that value.

[tex]3.14 \ mol \ PI_3 *\frac {411.687262 \ g \ PI_3}{ 1 \ mol \ PI_3}[/tex]

The units of moles of PI₃ cancel.

[tex]3.14 *\frac {411.687262 \ g \ PI_3}{ 1 }[/tex]

[tex]1292.698 \ g\ PI_3[/tex]

The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we calculated, that is the tens place.

The 2 in the ones place tells us to leave the 9.

[tex]1290 \ g \ PI_3[/tex]

3.14 moles of phosphorous triiodide is approximately equal to 1290 grams of phosphorus triodide.

Answer:

Phenolphthalein is a chemical compound with the formula C20H14O4 and is often written as "HIn" or "phph" in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions.

Answer:

Phenolphthalein is a chemical compound, a colorless crystalline solid, though pink in a alkaline solution, and is also used as an acid-base indicator.

Explanation:

Answer:

1.82g of Zn remain

Explanation:

Zinc, Zn, reacts with hydrochloric acid, HCl, as follows:

Zn + 2HCl → ZnCl2 + H2

Where 1 mole of Zn reacts with 2 moles of HCl

To solve this question we must find the moles of each reactant. With the moles of HCl we can find the moles of zinc needed for a complete reaction and the mass of zinc that remains:

Moles Zn -Molar mass: 65.32g/mol-

6.72g * (1mol / 65.38g) = 0.1028 moles Zn

Moles HCl:

100.0mL = 0.1000L * (1.50mol / L) = 0.150moles HCl

The moles of Zn that react with 0.150 moles HCl are:

0.150 mol HCl * (1mol Zn / 2mol HCl) = 0.075 moles of Zn are required

The moles that remain are:

0.1028 moles Zn - 0.075 moles of Zn = 0.0278 moles Zn

The mass is:

0.0278 moles Zn * (65.38g / mol) =

Answer: The new temperature is [tex]63^{o}C[/tex].

Explanation:

Given: [tex]V_{1}[/tex] = 1.90 L,    [tex]T_{1} = 21.0^{o}C[/tex]

[tex]V_{2}[/tex] = 5.70 L,         [tex]T_{2} = ?\\[/tex]

Formula used to calculate new temperature is as follows.

[tex]\frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}}[/tex]

Substitute the values into above formula as follows.

[tex]\frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}}\\\frac{1.90 L}{21.0^{o}C} = \frac{5.70 L}{T_{2}}\\T_{2} = 63^{o}C[/tex]

Thus, we can conclude that the new temperature is [tex]63^{o}C[/tex].

Answer:

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Answer:

Explanation:

acceleration is inversely proportional to the mass of an object.

Newton's second law states that "the acceleration produced on a body is directly proportional to the resultant force anf inversely proportional to its mass".