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3 years ago

How many oxygen atoms are in 2.80 g of quartz?

1 answer:

4 0

The chemical formula for quartz is SiO₂
Percentage by mass of oxygen = (2 x 16) x 100 / (28 + 2 x 16)
Percentage by mass of oxygen = 53.3%

Mass of oxygen in sample = 0.533 x 2.8
Mass of oxygen = 1.49 grams

Moles of oxygen = 1.49 / 16
Moles = 0.093

One mole contains 6.02 x 10²³ particles
Thus, the atoms of oxygen:
0.093 x 6.02 x 10²³
= 5.6 x 10²²

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Hydrogen is a reactive gas under normal conditions.Based on this property alone, to which group of the periodic table should hyd

denis23 [38]

Even though Hydrogen is originally in group 1, based on this property, we can say it is in group 6.

Because:

Group 6 would mean that it only needs 2 more valence electrons till the octet (8 valence electrons). This would make it reactive, yet, in normal conditions, unlike group 7.

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3 years ago

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A field worker is exposed to a xylene for a duration of 8 weeks at 40 hrs/wk. The concentration of xylene in the workplace is 40

Andrej [43]

Answer:

The chronic daily intake during the period of exposure is most nearly 0.012 mg/kg day.

Explanation:

Number of hours worker exposed to xylene = $40 hr/week\times 8 week = 320 hours$

The concentration of xylene in the workplace = $40 \mu g/m^3$

The worker is inhaling air at a rate of $0.9 m^3/hr$ .

Amount xylene inhaled by worker in an hour :

= $40\mu g/m^3\times 0.9 m^3/hr=36 \mu g/hr$

Amount xylene inhaled by worker in 320 hours:

$36 \mu g/hr\times 320 hr=11,520 \mu g=11,520\times 0.001 mg=11.520 mg$

1 μg = 0.001 mg

Amount xylene inhaled by worker in 320 hours = 11.520 mg

1 day = 24 hours

Amount xylene inhaled by worker in 1 day:

$\frac{24}{320}\times 11.520 mg=0.864 mg$

Assuming 70 kg body mass, the chronic daily intake of xylene :

$\frac{0.864 mg/day}{70 kg}=0.01234 mg/ kg day\approx 0.012 mg/ kg day$

The chronic daily intake during the period of exposure is most nearly 0.012 mg/kg day.

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2 years ago

What is the "reproductive system"

bija089 [108]

Answer: The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction

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2 years ago

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How do you write 561983 in scientific notation?

Artist 52 [7]

Answer:

5.61983 × 10^5

Explanation:

Move the decimal forward 5 spaces, each time doing so you add 10^(# of spaces moved, in this case 5)

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2 years ago

What can be deduced from the fact that a substance has a pH of 7?

balandron [24]

Answer:

Explanation:

A) The number of H+ ions in the substance is equal to the number of OH-ions.

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3 years ago