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steposvetlana [31]
3 years ago
7

The half life of potassium 40 is approximately 1.25 billion years. An igneous rock is found to contain about 1/4 of its original

mass of potassium 40. The approximate age of the rock is _____ billion years.
Chemistry
1 answer:
vodomira [7]3 years ago
4 0

Answer:

2.5 billion years

Explanation:

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For the chemical reaction
polet [3.4K]

Answer:

806.3g

Explanation:

Given parameters:

 Number of moles of silver nitrate  = 4.85mol

Unknown:

Mass of silver chromate = ?

Solution:

         2AgNO₃ + Na₂CrO₄  →  Ag₂CrO₄ + 2NaNO₃

To solve this problem, we work from the known to the unknown;

  • The known specie here is  AgNO₃ ;

   From the balanced chemical equation;

          2 moles of AgNO₃  will produce 1 mole of Ag₂CrO₄

          4.85 moles of AgNO₃  will produce \frac{4.85}{2}   = 2.43moles of Ag₂CrO₄

  • Mass of silver chromate produced;

        mass = number of moles x molar mass

   Molar mass of  Ag₂CrO₄

    Atomic mass of Ag = 107.9g/mol

                                 Cr  = 52g/mol

                                  O  = 16g/mol

  Input the parameters and solve;

     Molar mass  = 2(107.9) + 52 + 4(16) = 331.8g/mol

  So,

        Mass of Ag₂CrO₄ = 2.43 x 331.8 = 806.3g

     

8 0
3 years ago
What is the correct answer?
Dominik [7]

Answer:

Bleach and seawater are identified wrong.

Explanation:

Acids have an pH that is lower than 7 and bases have a pH of higher than 7 and (pH 7 is neutral)

We can observe from the table that bleach has a pH of 13 which is higher than 7 and shows basic characteristics

As for seawater the table shows it has a pH of 8 which is also a base. Therefore the answer is 3rd option "Bleach and seawater should be identified as bases".

8 0
3 years ago
A qué temperatura en grados centígrados se encuentra la Luna, si se sabe que está en 3 Kelvin aproximadamente?
Viktor [21]

Answer:

Can you do it in english please don't understand Spanish much. thanks

4 0
3 years ago
Which of the following is not a phase change?
sweet [91]
C. Diffusion is not a phase change.
6 0
3 years ago
A 1.0 g sample of hydrogen reacts completely with 19.0 g of fluorine to form a compound of hydrogen and fluorine. a. What is the
Rashid [163]

Explanation:tr

a) Molar mass of HF = 20 g/mol

Atomic mass of hydrogen = 1 g/mol

Atomic mass of fluorine = 19 g/mol

Percentage of an element in a compound:

\frac{\text{Number of atoms of element}\times \text{Atomic mass of element}}{\text{Molar mass of compound }}\times 100

Percentage of fluorine:

\frac{1\times 19 g/mol}{20g/mol}\times 100=95\%

Percentage of hydrogen:

\frac{1\times 1g/mol}{20 g/mol}\times 100=5\%

b) Mass of hydrogen in 50 grams of HF sample.

Moles of HF = \frac{50 g}{20 g/mol}=2.5 mol

1 mole of HF has 1 mole of hydrogen atom.

Then 2.5 moles of HF will have:

1\times 2.5 mol=2.5 mol of hydrogen atom.

Mass of 2.5 moles of hydrogen atom:

1 g/mol × 2.5 mol = 2.5 g

2.5 grams of hydrogen would be present in a 50 g sample of this compound.

c) As we solved in part (a) that HF molecules has 5% of hydrogen by mass.

Then mass of hydrogen in 50 grams of HF compound we will have :

5% of 50 grams of HF = \frac{5}{100}\times 50 g=2.5 g

8 0
3 years ago
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