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3 years ago

What is the half-life of Technetium-99 if a 200 gram sample decays to 50 grams in 639,000 years?

Chemistry

1 answer:

Elenna [48]3 years ago

5 0

Answer:

The half-life of Th-232 is 1.4 ∙ 10¹⁰ years.

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How many grams of dextrose are needed to make 725 mL of a 26.0% (w/v) dextrose solution? Note that mass is not technically the s

Diano4ka-milaya [45]

Answer:

188.5g of dextrose are needed

Explanation:

In Weight per volume percentage - %(w/v) -, the concentration is defined as the mass of solute in grams -In this case, dextrose-, in 100mL of solution.

As you want to prepare 725mL of a 26.0% (w/v) solution. you need:

725mL * (26g / 100mL) = 188.5g of solute =

<h3>188.5g of dextrose are needed</h3>

3 0

3 years ago

NH3 + H2O <br> How do I balance this

Alla [95]

Answer:

NH3 +H2O = NH4OH

Explanation:

no.of N atoms,O atoms and H atoms are now equal on both sides of the arrow.

5 0

3 years ago

What is the correct chemical name for the molecular compound if6?

Sati [7]

Iodine hexafluoride is the chemical name

5 0

3 years ago

Convert 6.71 moles NH3 to number of molecules.

svetlana [45]

Answer: There are $40.41 \times 10^{23}$ molecules present in 6.71 moles of $NH_{3}$ .

Explanation:

Given: Moles of $NH_{3}$ = 6.71 mol

According to the mole concept, 1 mole of every substance contains $6.022 \times 10^{22}$ molecules.

Therefore, molecules present in 6.71 moles are calculated as follows.

$Molecules = moles \times 6.022 \times 10^{23}\\= 6.71 \times 6.022 \times 10^{23}\\= 40.41 \times 10^{23}$

Thus, we can conclude that there are $40.41 \times 10^{23}$ molecules present in 6.71 moles of $NH_{3}$ .

6 0

3 years ago

C.Convert the following using the molar mass of each:

Alik [6]

Answer:

1. 1.145 mole

2. 19.368g

3. 66.67 moles

4. 0.0056g

Explanation:

The following calculations gives the answers to the various questions asked above:

1. Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

Mass of NaCl from the question = 67g

Number of mole NaCl =.?

Number of mole = Mass /Molar Mass

Number of mole NaCl = 67/58.5

Number of mole of NaCl = 1.145 mol

2. Number of mole of H2O = 1.076 mole

Molar Mass of H2O = (2x1) + 16 = 2 + 16 = 18g/mol

Mass of H2O =?

Mass = number of mole x molar Mass

Mass of H2O = 1.076 x 18

Mass of H2O = 19.368g

3. Molar mass of C6H12O6 = (12x6) + (12x1) + (16x6) = 72 + 12 + 96 = 180g/mol

Mass of C6H12O6 = 1.2x104g

Mole of C6H12O6 =.?

Number of mole = Mass /Molar Mass

Mole of C6H12O6 = 1.2x104/180

Mole of C6H12O6 = 66.67 moles

4. Molar mass of Br2 = 2 x 80 = 160g/mol

Mole of Br2 = 3.5x10^-5 moles

Mass of Br2 =?

Mass = number of mole x molar Mass

Mass of Br2 = 3.5x10^-5 x 160

Mass of Br2 = 5.6x10^-3 = 0.0056g

4 0

3 years ago

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