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3 years ago

Which of the following is a reason that a scientist would want to use a model to study DNA? A. DNA may not really exist

Chemistry

1 answer:

Otrada [13]3 years ago

7 0

I think it is D but i'm not sure

hope I helped :)

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An iron pipe has a density of 7.86 g/mL and a volume of 324.4 mL. What is the mass of the iron pipe?

wlad13 [49]

Answer:

$Mass=2549.784 \ g$

Explanation:

The equation for mass is:

$Mass = Density * Volume$

We plug in the given values into the equation:

$Mass = 7.86 \ g/mL * 324.4 \ mL$

$Mass=2549.784 \ g$

6 0

2 years ago

What is the hydrogen ion concentration of a solution with pH=8.25 ?

77julia77 [94]

Answer:

The answer is

<h2> $5.62 \times {10}^{ - 9} \: M$ </h2>

Explanation:

The pH of a solution can be found by using the formula

$pH = - log( {H}^{ + } )$

where

${H}^{ + }$ is the hydrogen ion concentration of the solution

From the question

pH = 8.25

The hydrogen ion concentration of the solution is

$8.25 = - log( {H}^{ + } )$

<u>Find antilog of both sides</u>

That's

${H}^{ + } = {10}^{ - 8.25} \\ = 5.62 \times {10}^{ - 9} \: M$

We have the final answer as

$5.62 \times {10}^{ - 9} \: M \\$

Hope this helps you

5 0

3 years ago

The decomposition of 57.0 g of Fe2O3 results in Consider the following reaction. 2Fe2O3 ---> 4Fe + 3O2 deltaH degree rxn = +

lozanna [386]

Answer:

The correct answer is option E.

Explanation:

$2Fe_2O_3\rightarrow 4Fe + 3O_2 \Delta H^o_{rxn} = 824.2 kJ$

Mass of ferric oxide decomposed = 57.0 g

Moles of ferric oxide decomposed = $\frac{57.0 g}{160 g/mol}=0.35625 mol$

According to reaction, 2 moles ferric oxide on combustion gives 824.2 kJ of heat.

Then heat given by on decomposition of 0.35625 mol of ferric oxide will be:

$\frac{824.2 kJ}{2}\times 0.35625 =146.81 kJ\approx 147 kJ$

So, on decomposition of 57.0 grams of ferric oxide 147 kilo Joules of heat was released.

3 0

3 years ago

8. A student filled a graduated cylinder with water and read the meniscus at 25.8 mL. The student

fomenos

Answer:

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

mass = Density × volume

volume = final volume of water - initial volume of water

From the question

volume = 35.9 ml - 25.8 ml = 10.1 mL

We have

mass = 2.99 × 10.1 = 30.199 g

We have the final answer as

Hope this helps you

5 0

3 years ago

During a titration the following data were collected. A 20.0 mL portion of solution of an unknown acid HX was titrated with 2.0

Dafna1 [17]

Answer:

The molarity of the acid HX is 6.0 M.

Explanation:

We determine the amount of moles of KOH used to neutralize the acid:

$\frac{2.0moles_{KOH}}{1000ml} *60ml$ =0.12 moles KOH

Then, we calculate the amount of moles of acid:

0.12 moles KOH× $\frac{1 mole HX}{1 moles KOH}$ =0.12 moles HX

The molarity of HX is:

$\frac{0.12 moles HX}{20ml} *\frac{1000ml}{1l}$ =6.0 M

8 0

3 years ago