Explanation:tr
a) Molar mass of HF = 20 g/mol
Atomic mass of hydrogen = 1 g/mol
Atomic mass of fluorine = 19 g/mol
Percentage of an element in a compound:
Percentage of fluorine:
Percentage of hydrogen:
b) Mass of hydrogen in 50 grams of HF sample.
Moles of HF = 
1 mole of HF has 1 mole of hydrogen atom.
Then 2.5 moles of HF will have:
of hydrogen atom.
Mass of 2.5 moles of hydrogen atom:
1 g/mol × 2.5 mol = 2.5 g
2.5 grams of hydrogen would be present in a 50 g sample of this compound.
c) As we solved in part (a) that HF molecules has 5% of hydrogen by mass.
Then mass of hydrogen in 50 grams of HF compound we will have :
5% of 50 grams of HF = 
Infrared radiation
Explanation:
The type of electromagnetic waves Jeff uses to make his goggles work are the infrared radiations.
Jeff is certainly using a night vision goggle to see in the dark . It senses infrared radiations
- Infrared radiations are part of the electromagnetic spectrum.
- Every hot objects gives off infrared radiations.
- These googles have thermal imaging sensors that detects these radiations.
- Naked eyes cannot see the radiations.
- The heat emitted is a form of radiation called the infrared radiation.
learn more:
Electromagetic radiation brainly.com/question/6818046
#learnwithBrainly
Hey i did this lab a few months ago!
Answer: <em>Newton's first law</em>
Explanation: <em>The idea that objects only change their velocity due to a force is encapsulated in Newton's first law. Newton's first law: An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force.</em>
<em />
Constant:
Test tubes
Independent:
<span>volume of gas
Dependent:
</span>
<span>amount of H2O2 </span>
