The mass of pentane the student should weigh out is
The density of pentane is 0.626 gcm-3
To calculate the mass of pentane following expression is used,
(Density is defined as the mass divide by volume)
Density = mass / volume
mass of pentane = Density of pentane * Volume of pentane
mass of pentane = 0.626 gcm-3 * 45.0 mL
= 28.17 g
Here the unit of mass of pentane is g,
However the unit of density is gcm-3 and unit of volume is mL i.e. cm3
Hence, Mass = gcm-3 * cm3
Mass = g
The mass of pentane the student should weigh out is 28.17g
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1. Hyaline: most common; found in the ribs, nose, trachea. Is a precursor of bone
2. Fibro: found in invertebral discs, joint capsules, and ligaments.
3. Elastic: found in the external ear, epiglottis, and larynx.
it is A Acid
Explanation : Any substance that yields a hydrogen ion when placed in a water solution is called an acid. According to Arrhenius theory of Acids and Bases, Acids are those substances which on dissociation in solution generates ions. Whereas a Base is a substance that dissociates in the solution to produce ions.
Answer:

Explanation:
2C₄H₁₀ + 13O₂ ⟶ 8CO₂ + 10H₂O
n/mol: 4.3
13 mol of O₂ react with 2 mol of 2C₄H₁₀

Hey there!:
Number of moles:
Molar Mass Al = 26.98 g/mol
n = mass / molar mass
n = 9.0 / 26.98
n = 0.3336 moles of Al
Given the reaction :
2 Al + Fe2O3 = Al2O3 + 2 Fe
From the equation, 2 moles of Al give off 849 kJ of heat :
Actual heat given off :
0.3336 / 2 * 849 =
0.3336 / 1698 = 1.4*10² Kj
Hope that helps!