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Dominik [7]
3 years ago
10

The compound diborane can be used as a rocket propellant. What is the percent composition of boron in diborane (B2H6)? A. 22% B.

25% C. 39% D. 75% E. 78%
Chemistry
1 answer:
sveticcg [70]3 years ago
4 0

Answer: E. 78%

Explanation:

Diborane (B2H6), a chemical compound made up of approximately 78% Boron and 22% Hydrogen.

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A sample of a food label is shown below.
White raven [17]

Answer:

A) It's correctly written

B) 77%

C) 835 calories

Explanation:

A) From online sources, we have number of calories as follows;

Fats: 9 calories per gram

Protein; 4 calories per gram

Carbs; 4 calories per gram

Total calories for each;

Total fat = 3 × 9 = 27 calories

Total protein = 3 × 4 = 12 calories

Total carbs = 32 × 4 = 128 calories

(sugar and dietary Fibre are classified as carbohydrates and so total carbs takes care of their calories).

Thus, total number of calories per serving = 27 + 12 + 128 = 167 calories per serving which is same as what is given.

B) percent from carbohydrates per serving = total calories from carbs/total number of calories per serving × 100% = 128/167 × 100% ≈ 77%

C) One box contains 5 servings. Thus total number of calories per box = 167 × 5 = 835 calories

8 0
3 years ago
How much heat is absorbed in the complete reaction of 3.00 grams of SiO2 with excess carbon in the reaction SiO2(g) + 3C(s) → Si
defon

Answer:

31.24 kJ

Explanation:

  • SiO₂(g) + 3C(s) → SiC(s) + 2CO(g)        ΔH° = 624.7 kJ/mol

First we <u>convert 3.00 grams of SiO₂ to moles</u>, using its <em>molar mass</em>:

  • 3.00 g SiO₂ ÷ 60.08 g/mol = 0.05 mol

Now we <u>calculate the heat absorbed</u>, using the <em>given ΔH°</em>:

If the complete reaction of 1 mol of SiO₂ absorbs 624.7 kJ, then with 0.05 mol:

  • 0.05 mol * 624.7 kJ/mol = 31.24 kJ of heat would be absorbed.
6 0
3 years ago
3. How did organizing the periodic table by atomic number help scientists?
forsale [732]
Scientists developed symbols and gave the elements numbers to help organize the elements by their chemical properties. The periodic table helps identify the underlying chemical and physical traits of the elements.
4 0
3 years ago
Which scientist was the first to use the telescope in astronomy? Copernicus Newton Kepler Galileo
coldgirl [10]

The scientist that was the first to use the telescope in astronomy was Newton

8 0
3 years ago
What change takes place in a nuclear fusion reaction?
irakobra [83]
A nuclear reaction<span> in which two or more atomic nuclei come very close and then collide at a very high speed and join to form a new type of atomic nucleus.
      Hope this helps :)
</span>
7 0
4 years ago
Read 2 more answers
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