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SpyIntel [72]
3 years ago
7

Mass and energy are conserved Question 13 options: A) only in chemical changes. B) always in physical changes and sometimes in c

hemical changes. C) only in physical changes. D) in chemical changes and physical changes.
Chemistry
1 answer:
Roman55 [17]3 years ago
3 0

Answer:

B

Explanation:

sometimes it can change chemically but not all the time.

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0.57 centimeter to meter
uysha [10]
If 100cm is 1 metre
Then 0.57 cm =

If less more divides,
Hence 100÷0.57 × 1



= 0.0057 Metres.
6 0
3 years ago
According to the Brinsted -Lowry. what is an acid ? what is a base ? ​
sasho [114]

Answer:

According to the Brønsted definition, an acid is a substance capable of donating a proton, and a base is a substance capable of accepting a proton. ... The species giving up the proton is HCl, an acid. The species accepting the proton is water, the base. The species Cl- is the conjugate base of HCl.

8 0
3 years ago
2. What is the name of the following compound? *
alexgriva [62]
Answer: Cesium Nitrate
4 0
3 years ago
When a magnesium ribbon is heated in air the product former is heavier.on the other hand when potassium manganate(VII) is heated
vesna_86 [32]

Answer: On heating, Magnesium forms its oxide; while potassium manganate(VII) decomposes

Explanation:

Magnesium Mg, on heating forms Magnesium oxide

2Mg(s) + O2(g) --> 2MgO

Potassium permanganate KMnO4, on heating decomposes to potassium manganate K2MnO4, manganese dioxide MnO2, and Oxygen gas O2.

2KMnO4 --> K2MnO4 + MnO2 + O2

The difference in observation is that, on heating, Magnesium forms its OXIDE as product; while potassium manganate(VII) decomposes, giving OFF most of its constituents and reducing its weight.

4 0
3 years ago
How many molecules are in 7.62 L of CH4, at 87.5°C and 722 torr
pickupchik [31]

Answer: There are 1.469 \times 10^{23} molecules present in 7.62 L of CH_4 at 87.5^{o}C and 722 torr.

Explanation:

Given : Volume = 7.62 L

Temperature = 87.5^{o}C = (87.5 + 273) K = 360.5 K

Pressure = 722 torr

1 torr = 0.00131579

Converting torr into atm as follows.

722 torr = 722 torr \times \frac{0.00131579 atm}{1 torr}\\= 0.95 atm

Therefore, using the ideal gas equation the number of moles are calculated as follows.

PV = nRT

where,

P = pressure

V = volume

n = number of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

PV = nRT\\0.95 atm \times 7.62 L = n \times 0.0821 L atm/mol K \times 360.5 K\\n = \frac{0.95 atm \times 7.62 L}{0.0821 L atm/mol K \times 360.5 K}\\= \frac{7.239}{29.59705}\\= 0.244 mol

According to the mole concept, 1 mole of every substance contains 6.022 \times 10^{23} atoms. Hence, number of atoms or molecules present in 0.244 mol are calculated as follows.

0.244 mol \times 6.022 \times 10^{23}\\= 1.469 \times 10^{23}

Thus, we can conclude that there are 1.469 \times 10^{23} molecules present in 7.62 L of CH_4 at 87.5^{o}C and 722 torr.

5 0
3 years ago
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