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k0ka [10]
3 years ago
15

When a log burns in a fire, a a physical change has occurred. b mass is gained. c new substances are formed.

Chemistry
2 answers:
Pavlova-9 [17]3 years ago
8 0

Answer: technically it is chemical and physical change

Explanation: chemical bc it’s burning and physical bc it’s going from a log to ashes

Zepler [3.9K]3 years ago
5 0

Answer:

C! New substances are formed.

Explanation:

The burning log will release carbon dioxide, which is a new substance that was never there in the first place.

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A container is filled with helium gas. It has a volume of 2.25 liters and contains 9.00 moles of helium. How many moles of heliu
Darina [25.2K]

Answer: There are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.

Explanation:

Given: V_{1} = 2.25 L,     n_{1} = 9.0 mol

V_{2} = 1.85 L,            n_{2} = ?

Formula used to calculate the moles of helium are as follows.

\frac{V_{1}}{n_{1}} = \frac{V_{2}}{n_{2}}\\

Substitute the values into above formula as follows.

\frac{V_{1}}{n_{1}} = \frac{V_{2}}{n_{2}}\\\frac{2.25 L}{9.0 mol} = \frac{1.85 L}{n_{2}}\\n_{2} = \frac{1.85 L \times 9.0 mol}{2.25 L}\\= 7.4 mol

Thus, we can conclude that there are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.

7 0
3 years ago
What type of compound is almost always found as a solid?
Evgesh-ka [11]
Hi , your answer is Ionic.
4 0
3 years ago
Read 2 more answers
4.564000 x 10^-4 express how many significant figures
Vaselesa [24]

Answer: 7

Explanation:

Before a number but after a decimal. The zeros at the end would usually mean that it doesn't count but since the numbers are before the zeros and after a decimal it's 7 sig figs

5 0
3 years ago
What is the volume of 0.80 grams of O2 gas at STP? (5 points) Group of answer choices 0.59 liters 0.56 liters 0.50 liters 0.47 l
Anarel [89]

Answer:

0.56 liters

Explanation:

First we <u>convert 0.80 grams of O₂ into moles</u>, using its molar mass:

  • 0.80 g ÷ 32 g/mol = 0.025 mol

At STP, 1 mol of any given mass occupies 22.4 L. With that information in mind we <u>calculate the volume that 0.025 moles of O₂ gas would occupy</u>:

  • 0.025 mol * 22.4 L/mol = 0.56 L

Thus the answer is 0.56 liters.

3 0
3 years ago
A solution is prepared by dissolving 0.23 mol of benzoic acid and 0.27 mol of sodium benzoate in water sufficient to yield 1.00
Monica [59]

Answer:

The pH does not decrease drastically because the NaOH reacts with the <u>D) Benzoic acid</u> present in the buffer solution.

Explanation:

The hydroxide ions will react with acidic part of the solutions, it means the benzoic acid, so it will form the conjugate base, the benzoate ion.

7 0
3 years ago
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