I NEED HELP. This is about science

Explanation:

b and c statements are not true

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Answer:

B.) Smoking improves Athletic performance

Explanation:

Given

Lf=latent heat of fusion  of Al = 95 cal/g

Q = 1,265,730 cal

Required

mass of Aluminium

Solution

The heat to change the phase can be formulated :

Q = m.Lf (melting/freezing)

Input the value

1,265,730 cal = m . 95 cal/g

m = 1,265,730 cal : 95 cal/g

m = 13323.47 g

Find your answer in the explanation below.

Explanation:

PV = nRT is called the ideal gas equation and its a combination of 3 laws; Charles' law, Boyle's law and Avogadro's law.

According to Boyle's law, at constant temperature, the volume of a gas is inversely proportional to the pressure. i.e V = 1/P

From, Charles' law, we have that volume is directly proportional to the absolute temperature of the gas at constant pressure. i.e V = T

Avogadro's law finally states that equal volume of all gases at the same temperature and pressure contain the same number of molecules. i.e V = n

Combining the 3 Laws together i.e equating volume in all 3 laws, we have

V = nT/P,

V = constant nT/P

(constant = general gas constant = R)

V = RnT/P

by bringing P to the LHS, we have,

PV = nRT.

Q.E.D

Answer:

Number of moles of water = 210 mol

Explanation:

Given data:

Mass of water = 3780 g

Number of moles of water = ?

Solution:

Formula:

Number of moles = mass/molar mass

Molar mass of water = 18 g/mol

Number of moles = 3780 g/ 18 g/mol

Number of moles of water = 210 mol

Answer:

Transition elements are present in this region.

Explanation:

Answer:

yes

Explanation:

its not that hard to get

Answer:

I think the answer is true

The name of a molecule which is composed of two phosphorous atoms and four sulfur atoms is phosphorus sulphide.

According on the context, the word may or may not include ions that meet this requirement. A molecule is a collection of two or more atoms bound together by attractive forces known as chemical bonds.

A molecule is the smallest unit of any material that is composed of one or more elements and is capable of existing independently while maintaining all of the substance's physical and chemical characteristics. Further atom division occurs within molecules. For instance, the symbols for the oxygen atom and molecule are O and O2, respectively.

Thus, The name of a molecule which is composed of two phosphorous atoms and four sulfur atoms is phosphorus sulphide.

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Answer:

12.5%

Explanation:

From the question given above, the following data were obtained:

Half-life (t½) = 2 h

Time (t) = 6 h

Percentage remaining =.?

Next we shall determine the number of half-lives that has elapse. This can be obtained as follow:

Half-life (t½) = 2 h

Time (t) = 6 h

Number of half-lives (n) =?

n = t / t½

n = 6/2

n = 3

Finally, we shall determine the percentage of original dosage remaining as follow:

Amount remaining (N) = Original amount (N₀) /2ⁿ

N = N₀ / 2ⁿ

Divide both side by N₀

N/N₀ = 1/2ⁿ

Input the value of n i.e 3

N/N₀ = 1/2³

N/N₀ = 1/8

N/N₀ = 0.125

Multiply by 100 to express in percent.

N/N₀ = 0.125 × 100

N/N₀ = 12.5%

Thus, percentage of original dosage remaining is 12.5%

Answer: The lewis dot structure is attached below.

Explanation:

A Lewis dot structure is defined as the representation of atoms having electrons around the atom where electrons are represented as dots.

A ketene is an organic compound having general formula R′R″C=C=O, where R and R' are two different/same monovalent chemical groups.

The given chemical compound having formula [tex]C_2H_2O[/tex] is represented as [tex]H_2-C=C=O[/tex].

Total number of unshared electrons = 4 (left on oxygen atom only)

The lewis dot structure of [tex]C_2H_2O[/tex] is given in the image below.

The volume of concentrated HCl : 2.073 ml

Given

37% HCl by mass; density 1.19 g/mL

Required

The volume of concentrated HCl

Solution

Conversion to molarity :

37% x 1.19 g/ml =0.4403 g/ml

g/ml to mol/L :

=0.4403 g/ml x 1000 ml/L : 36.5 g/mol

=12.06 mol/L

or we can use formula :

[tex]\tt M=\dfrac{\%\times \rho\times 10}{MM}\\\\M=\dfrac{37\times 1.19\times 10}{36.5}\\\\M=12.06[/tex]

Dilution formula :

M₁V₁=M₂V₂

12.06 M x V₁ = 0.1 M x 0.25 L

V₁ = 0.0021 L = 2.073 ml

The percentage yield of copper = 76%

Given

6.5g of Zinc

The mass of Copper: 4.8 g

Required

The percentage yield of copper

Solution

Reaction

Zn+CuSO₄⇒Cu+ZnSO₄

mol Zn :

= mass : Ar Zn

= 6.5 g : 65,38 g/mol

= 0.0994

From the equation, mol ratio of Zn : Cu = 1 : 1, so mol Cu = 0.0994

Mass Cu (theoretical) :

= mol x Ar Cu

= 0.0994 x 63,546

= 6.316 g

%yield = (actual/theoretical) x 100%

%yield = (4.8/6.316) x 100%

%yield = 76%

Answer:

1. expanding

2. red, blue

3. red, spreading out

Explanation:

Answer:

21

Explanation:

To find the total atoms.

Multiply 3 *2 and you will get 6

Then multiply 3 * 5 and you will get 15.

You do this because there is 3 as a coefficient and is before the chemical compound. Furthermore, that means the same thing as a parenthesis.

Last of all, add 15 + 6 and you will get 21.

Therefore, there are a total of 21 atoms.

Answer:

62.07 %

Explanation:

Chemical Formula =  (CH3)2CO = C3H6O

Mass of C = 12 g/mol

Mass of H = 1 g/mol

Mass of O = 12 g/mol

Mass of  C3H6O = 3(12) + 6(1) + 16 = 58 g/mol

Total mass of C in Acetone = 12 * 3 = 36 g

Mass Percent of C =  Total mass of C / Mass of Acetone   *  100

Mass percent = 36 / 58    *  100

Mass percent = 62.07 %

Answer:

1.510 × 10⁻¹³ g

Explanation:

Step 1: Given data

Number of atoms of vanadium: 1.000 × 10⁹ atoms

Step 2: Calculate the molecules of V₂O₅ that contain 1.000 × 10⁹ atoms of V

Each molecule of V₂O₅ has 2 atoms of V.

1.000 × 10⁹ atom V × (1 molecule V₂O₅/2 atom V) = 0.5000 × 10⁹ molecule V₂O₅

Step 3: Calculate the moles corresponding to 0.5000 × 10⁹ molecules of V₂O₅

We will use Avogadro's number: there are 6.022 × 10²³ molecules of V₂O₅ in 1 mole of V₂O₅.

0.5000 × 10⁹ molecule × (1 mol/6.022 × 10²³ molecule) = 8.303 × 10⁻¹⁶ mol

Step 4: Calculate the mass corresponding to 8.303 × 10⁻¹⁶ moles of V₂O₅

The molar mass of V₂O₅ is 181.88 g/mol.

8.303 × 10⁻¹⁶ mol × 181.88 g/mol = 1.510 × 10⁻¹³ g

Answer:

63.7g BaCl₂

Explanation:

Based on the chemical reaction:

2HCl + Ba(OH)₂ → BaCl₂ + 2H₂O

2 moles of HCl reacts per mole of barium hydroxide

To solve this question, we need to convert the moles of each reactant to moles and, using the chemical reaction, find limiting reactant as follows:

Moles Ba(OH)₂ - Molar mass: 171.34g/mol-

52.4g Ba(OH)₂ * (1mol / 171.34g) = 0.306 moles Ba(OH)₂

Moles HCl - Molar mass: 36.46g/mol-

25.6g HCl * (1mol / 36.46g) = 0.702 moles HCl

For a complete reaction of 0.702 moles HCl are required:

0.702 moles HCl * (1mol Ba(OH)₂ / 2mol HCl) = 0.351 moles of Ba(OH)₂

As there are just 0.306 moles, limiting reactant is Ba(OH)₂

That means the maximum amount of BaCl₂ produced is:

0.306 moles Ba(OH)₂ * (1mol BaCl₂ / 1 mol Ba(OH)₂) = 0.306 moles BaCl₂

In mass -Molar mass BaCl₂: 208.23g/mol-

0.306 moles BaCl₂ * (208.23g / mol) = 63.7g BaCl₂

Explanation:

Fe. O

72.40/ 56 27.60/16

____________________

1.29/1.29 1.725/1.29

_____________________

1. :. 1

Empirical formula is the whole number ratios of elements in a compound. It can be found from the number of moles. The empirical formula of iron and oxygen of 72.4 % and 27.6 % respectively is Fe₂O₃.

Empirical formula of a compound is the chemical formula derived from the number of moles each element present in it.  Whereas, molecular formula is derived from the actual masses of the elements present in the compound.

Empirical formula can be determined from the number of moles of the elements. It is given that the mass percentages of iron and oxygen are 72.40% and 27.60% respectively. This can be taken as 72.40 g and 27.60 g in a 100 g of compound.

Thus there is 72.40 g of iron. The atomic mass of Fe = 55.85 g/mol

Thus number of moles of Fe = 72.40 / 55.85

                                               = 1.295

The weight of oxygen in 100 g of compound is 27.60 g. Atomic mass of oxygen is 16 g/mol.

Thus number of moles of oxygen = 27.60 /16 = 1.725

Taking the ratios of these number of moles = 1.295 :1.725 = 2 :3

Hence, the ratios of iron to oxygen is 2:3 which means the empirical formula of the compound is Fe₂O₃.

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Answer:

increases

and the 2nd one increases

Answer: [tex]K_2SO_4(aq)+2NaOH(aq)\rightarrow Na_2SO_4(aq)+2KOH(aq)[/tex]

Explanation:

A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.  

The balanced chemical equation is:

[tex]K_2SO_4(aq)+2NaOH(aq)\rightarrow Na_2SO_4(aq)+2KOH(aq)[/tex]

Answer: increase the bicycles acceleration hope this helps :]

Explanation:

Answer: 184 g of nitrogen dioxide that are produced from 4 moles of nitric oxide

Explanation:

The balanced chemical reaction is:

[tex]2NO(g)+O_2(g)\rightarrow 2NO_2(g)[/tex]  

According to stoichiometry :

2 moles of [tex]NO[/tex] produce = 2 moles of [tex]NO_2[/tex]

Thus 4 moles of [tex]NO[/tex] will require=[tex]\frac{2}{2}\times 4=4moles[/tex]  of [tex]NO_2[/tex]

Mass of [tex]NO_2=moles\times {\text {Molar mass}}=4moles\times 46g/mol=184g[/tex]

Thus 184 g of nitrogen dioxide that are produced from 4 moles of nitric oxide

Answer:

D. Atoms are changed into new elements.

Explanation:

atoms rearrange to form one or more different substances.

Hope that helps!!!

Sorry if its worng :(

Answer:

It's actually C. Energy is given off or absorbed.

Explanation:

"All chemical reactions involve changes in energy. This may be a change in heat, electricity, light, or other forms of energy. Reactions that absorb energy are endothermic. Reactions that release energy are exothermic."

-LibreTexts Chemistry

Answer:

It would be the last one because the way earth is tilted the sun rays would be pointing at the Northern Hemisphere more than the Southern Hemisphere