3) Convert 0.987 moles of Lithium to grams.

When investigative officers get to a crime scene, they do not need to collect water samples.

A crime scene is a place where an offence has been committed. It is usually cordoned off to enable investigation of the crime and the collection of samples.

When investigative officers get to a crime scene, they do not need to collect water samples.

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Answer:A

Explanation:.

Answer:

need more info

Explanation:

i think so we need more info

Answer:

c. one must have a higher kinetic energy than the other system

Answer:

4.041 moles C₂H₆

Explanation:

To convert from grams to moles, you first need to determine the molar mass of C₂H₆. The molar mass is the combination of the atomic masses times the quantity of each element present in the molecule. The atomic masses usually be found on the periodic table. They represent how much the element weighs per one mole.

Carbon (C) Atomic Mass: 12.01 g/mol

Hydrogen (H) Atomic Mass: 1.008 g/mol

Molar Mass (C₂H₆): 2(12.01 g/mol) + 6(1.008 g/mol)

Molar Mass (C₂H₆): 30.068 g/mol

Now that you have the molar mass, you can multiply this ratio to the given value. Keep in mind that in order to go from grams to moles, the numerical value should be place in the denominator of the molar mass ratio. This allows for the cancellation of the unit 'grams'. The final answer should have 4 significant figures because the given value also has 4 sig figs.

121.5 grams C₂H₆              1 mole
--------------------------  x  ------------------------  =  4.041 moles C₂H₆
                                     30.068 grams

Answer:

B and D

Explanation:

6 abundant elements-

1. oxygen

2. carbon

3. hydrogen

4. nitrogen

5. sulfur

6. phosphorus

Answer:

Phosphorus and Oxygen

Explanation:

Carbon is the most abundant element in our universe then comes oxygen then comes hydrogen.

Sulfur and nitrogen are also counted among most abundant elements

Option B and D are correct

By convention, the standard enthalpy of formation of all elements in their standard states are assumed to be zero. Here the enthalpy value for the intermediate formation step is  -572 kJ. The correct option is D.

The standard enthalpy of formation of a compound is defined as the enthalpy change accompanying the formation of one mole of the compound from its constituent elements, all the substances being in their standard states.

The symbol used to represent the standard enthalpy of formation is ΔfH⁰.  The knowledge of standard enthalpies of various substances is useful for calculating the standard enthalpies of a reaction.

The overall energy difference between the reactants and products remains the same no matter how many intermediates there are in the reaction pathway.

The enthalpy value  = 2 × -286 = -572 kJ

Thus the correct option is D.

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Answer:

4.87 g

Explanation:

The formula between the number of moles, mass and Mr can be used to find the mass of barium.

Number of moles = mass ÷ Mr

So, mass = number of moles × Mr

  Mr of Ba = 137.3

∴ Mass = (3.55 × 10⁻²)  × 137.3 = 4.87 g

Answer:

Burning of paper and log of wood.

Digestion of food.

Boiling an egg.

Explanation:

The concentration of the NaOH solution required for the reaction given the data is 0.44 M

H₂SO₄ + 2NaOH —> Na₂SO₄ + 2H₂O

From the balanced equation above,

CaVa / CbVb = nA / nB

(0.1 × 22) / (Cb × 10) = 1 / 2

2.2 / (Cb × 10) = 1 / 2

Cross multiply

Cb × 10 = 2.2 × 2

Cb × 10 = 4.4

Divide both side by 10

Cb = 4.4 / 10

Cb = 0.44 M

Thus, the concentration of the NaOH solution is 0.44 M

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The AH for the reaction is -137 kJ

Enthalpy of formation is the energy required by reactants to convert into products . It value can be positive or negative depending on the type of reaction, Endothermic or Exothermic.

In the question 3 step reaction is given

C₂H4 (g) + 3 O₂ (g) → 2 CO₂ (g) + 2 H₂O (1)   AH = - 1411. KJ

2 C₂H6 (g) + 7 O₂ (g) → 4 CO₂ (g) + 6 H₂O (1)   AH = - 3120. KJ

2 H₂ (g) + O₂ (g) → 2 H₂O (1)     AH = -571.6 kJ

To determine the enthalpy of formation for

C₂H4 (9) + H₂ (9)→ C₂H6 (g)

Adding reaction 1 and (1/2) 3 will give

C₂H4 (g) + 7/2 O₂ (g) + H₂ (g) ----> 2 CO₂ (g) + 3H₂O AH = -1696.8

For the second reaction

We will reverse the reaction and multiply it by 1/2

2 CO₂ (g) + 3 H₂O (1) -->  C₂H6 (g) + 7/2 O₂ (g)  AH = +1560

Adding the two new reactions.

C₂H4 (9) + H₂ (9)→ C₂H6 (g)    AH = -137 kJ

Therefore The AH for the reaction is -137 kJ

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From the calculations, the equilibrium constant of the reaction is given as   0.050

The term equilibrium constant refers to the number that shows the extent to which reactants are converted into products.

The equilibrium constant of this reaction can be obtained from;

K = [0.050] [1.00]^4

K = 0.050

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Refraction is caused due to the change in speed of light when it enters from one medium to another. Hence, option B is correct.

Refraction happens when light changes direction, or bends when it moves from one material to another.

The cause of the refraction of light is that light travels at different speeds in different media.

This change in the speed of light when it moves from one medium to another causes it to bend.

Thus, refraction is caused due to the change in speed of light when it enters from one medium to another. Hence, option B is correct.

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Answer:

 hydrogen gas will occupy 0.0374 liters when is cooled to 83 °C.

Explanation:

• T1 =602 °C = 875 K

• V1 =92 mL = 0.092 L

0.092L/875K= 1.05×10-⁴L/K

vf =nR/P T f= 1.05×10-⁴L/K ×356K

=0.0374 L

The molecular formula of the compound is C₄H₈O₄.

The molecular formula is the exact whole number ratio of the compound's elements. The empirical formula, as well as the molecular mass, are combined to generate the molecular formula.

Let's assume that the compound contains:

The empirical formula of the compound is:

C               H           O

40.6/12    5.1/1         54.2/16

3.38          5.1           3.38

Divide by the smallest value

3.38/3.38  5.1/3.38  3.38/3.38

1                  1.5≅ 2       1

= C₁H₂O₁

The empirical formula weight = (1 × 12) + (2 × 1) + (1 × 16)

The empirical formula weight = 30 g/mol

Molecular formula = (118.084 g/mol)/30 g/mol

Molecular formula = 3.94 ≅ 4

Therefore, the molecular formula for the compound is C₄H₈O₄.

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Answer:

0.82 M

Explanation:

You have been given moles and volume (in mL). To find the molarity of the solution, you need to (1) convert mL to L and then (2) plug moles and volume into the molarity formula.

985 mL / 1,000 = 0.985 L

Molarity (M) = moles / volume (L)

Molarity = 0.81 moles / 0.985 L

Molarity = 0.82 M

Answer:

When sodium metal is dropped in water, hydrogen gas is evolved. Thus, the reaction is, 2Na+2H2O→H2+2NaOH. In the reaction, sodium hydroxide is formed and hydrogen gas is evolved.

Explanation:

Answer:

0.0315 moles CH₂OH

Explanation:

You can find the amount of moles using the molarity equation. This equation looks like this:

Molarity (M) = moles / volume (L)

Once you convert mL to L (by dividing by 1,000), you can plug the molarity and volume into the equation and isolate to find moles. The final answer should have 3 sig figs because the given value with the lowest amount of sig figs (0.210 M) has this amount.

150.0 mL / 1,000 = 0.1500 L

Molarity = moles / volume

0.210 M = moles / 0.1500 L

(0.210 M x 0.1500 L) = moles

0.0315 = moles

Answer:

10.41 g

Explanation:

ml and   cm^3   are generally interchangeable

15 cm^3     *   . 694  g/cm^3 =  10.41 g

5.1434 contains 5 significant figures and 4 decimals.

All zeros that occur between any two non-zero digits are significant. For example, 108.0097 contains seven significant digits.

Calculation:

5.1234 + 0.033÷ 1.650 = 5.1434

5.1434 contains 5 significant figures and 4 decimals. 5.1434 rounded to 4 sig figs is 5.143, to 3 sig figs is 5.14, and to 2 sig figs is 5.1.

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Answer:

Explanation:

Comment

A: is in group 1. The properties are quite similar

B: the choices for answer B are in column or group 2. They too will have similar properties.

C: the choices there are in group 18. They do have similar properties.

The answer is D.

Note: group means the same thing as column. They are vertical.

Answer:

Copper (Cu2) , Iron (Fe2+ Fe3 +) , and Hydrogen ion (H+)

Explanation:

I hope it helps u dear! ^_^

Answer:

Because the brain is connected.

Explanation:

Based on the dilution formula, 0.1 mL of the stock solution of the enzyme is required to prepare a 50-fold diluted enzyme in 0.01 M HCl.

The 50-fold dilution of the stock enzyme solution can be done by using the dilution formula to determine the given volume of the stock solution required.

The dilution formula is given below:

where:

From the given data for the enzyme dilution;

C1 = 1

C2 = 1/50 = 0.02

V1 = x

V2 = 5 ml

Making V1 subject of formula in the dilution formula:

V1 = C2V2/C1

V1 =  0.02 * 5/1 = 0.1 mL

Therefore, 0.1 mL of the stock solution of the enzyme is required to prepare a 50-fold diluted enzyme in 0.01 M HCl.

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Answer:

B.

Explanation:

The amount of space between the particles in a medium reduces as its density rises, which causes light to bend. 2. This impact is highest for light that is close to the medium's surface and weakest for light that is far away from the medium's surface.

Answer:

2H2O+O2-2H2O2

Explanation:

TO BALANCE equation both side should be equal

Answer:

1.) There are 6 carbons in the longest possible parent chain (hex-). Since there is a double bond, this is an alkene.  The lowest possible carbon the double bond consists of is the 2nd carbon. There is also a methyl group on the 2nd carbon. All together, this makes the structure: 2-methyl-2-hexene.

2.) There are 9 carbons in the longest possible parent chain (non-). The lowest possible carbons the methyl groups are on are the 3rd and 5th carbons. The lowest possible carbon the ethyl group is located on is the 4th carbon. Remember, branches are listed alphabetically. All together, this makes the structure: 4-ethyl-3,5-dimethylnonane.

3.) There are 7 carbons in the longest possible parent chain (hept-). There is a triple bond, making this an alkyne. The lowest possible carbon the triple bond consists of is the 2nd carbon. The lowest possible carbon the methyl group is on is the 4th carbon. All together, this makes the structure: 4-methyl-2-heptyne.

4.) There are 10 carbons in the longest possible parent chain (dec-). The lowest possible carbon the propyl group is on is the 5th carbon. All together, this structure is: 5-propyldecane.

5.) There are 4 carbons in the longest possible parent chain (but-). The lowest possible carbon the methyl group is on is the 2nd carbon. All together, this makes the structure: 2-methylbutane.

6.) There are 5 carbons in the longest possible parent chain (pent-). There is a double bond, making the molecule an alkene. The lowest possible carbon the double bond consists of is the 2nd carbon. The lowest possible carbon the methyl group is on is the 2nd carbon. All together, this makes the structure: 2-methyl-2-pentene.

The heat that is released by the combustion of 3.5 moles of methane is 3115 kJ/mol.

A thermochemical equation is a reaction equation that incorporates the amount of heat lost/gained.

In this case, the reaction equation is; CH4 + O2 ----->CO2 + 2H2O dH = -890 kJ/mol

If 1 mole of methane releases 890 kJ/mol

3.5 moles of methane will release 3.5 moles * 890 kJ/mol/1 mole

= 3115 kJ/mol

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