Answer:
a mixture of molecules - Box f
atoms of a pure elementa metal - Box D
a solid compound - Box C
a mixture of elements - Box A
Explanation:
Box a has mixture of elements which forms a solid like shape but there are different elements present in the box. The box f has mixture of molecules in which many atoms are combined together. Box c has solid compound with single element.
☃️ Chemical formulae ➝ 
<h3>
<u>How to find?</u></h3>
For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.
<h3>
<u>Solution:</u></h3>
Atomic weight of elements:
Ca = 40
C = 12
O = 16
❍ Molecular weight of
= 40 + 12 + 3 × 16
= 52 + 48
= 100 g/mol
❍ Given weight: 10 g
Then, no. of moles,
⇛ No. of moles = 10 g / 100 g mol‐¹
⇛ No. of moles = 0.1 moles
☄ No. of moles of Calcium carbonate in that substance = <u>0.1 moles</u>
<u>━━━━━━━━━━━━━━━━━━━━</u>
Answer:
T₂ = 506.6 K
Explanation:
Given data:
Initial pressure of gas = 25°C (25+273 =298 K)
Initial temperature = 0.500 atm
Final pressure = 0.850 atm
Final temperature = ?
Solution:
According to Gay-Lussac Law,
The pressure of given amount of a gas is directly proportional to its temperature at constant volume and number of moles.
Mathematical relationship:
P₁/T₁ = P₂/T₂
Now we will put the values in formula:
0.500 atm / 298 K = 0.850 atm /T₂
T₂ = 0.850 atm × 298 K / 0.500 atm
T₂ = 253.3 atm. K / 0.500 atm
T₂ = 506.6 K
Answer: Significant figures in a measurement are all measured digits, and one estimated digit
Significant figures communicate the level of precision in measurements Significant figures are an indicator of the certainty in measurements.
Explanation:
Significant figures : The figures in a number which express the value or the magnitude of a quantity to a specific degree of accuracy or precision is known as significant digits.
The significant figures of a measured quantity are defined as all the digits known with certainty and the first uncertain or estimated digit.
Rules for significant figures:
1. Digits from 1 to 9 are always significant and have infinite number of significant figures.
2. All non-zero numbers are always significant.
3. All zero’s between integers are always significant.
4. All zero’s preceding the first integers are never significant.
5. All zero’s after the decimal point are always significant.
