Beryllium is a chemical element with symbol Be and atomic number 4. It is a relatively rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays.
Answer:
1) Hydrogen
2) Methane
3) Carbon
4) Structural isomer
5) Ethene also known as ethylene
6) Hydrocarbons are widely used as fuel
7) Crude oil
Explanation:
<u>Answer:</u>
(A)
Density = Mass / Volume
So
Mass = Density × Volume
Mole ratio of toluene : Oxygen is 1 : 9
(B)
1 mole of Toluene produces 7 moles of 
gas and 4 moles of 
Vapour
So the mole ratio is 1 : 11
(C)
1mole contains 
molecules
Using accurate measurements, using pure chemicals and performing the reaction under the most ideal conditions is important to get a valuable percent yield.
<h3>How we calculate the percent yield?</h3>
Percent yield of any chemical reaction is define as the ratios of the actual yield to the theoretical yield of the product and multiply by the 100.
To get the high percent yield or actual yield of any reaction, we have to perform the reaction under ideal condition because if we not use the standard condition then we get the low rate of reaction. Reactants should be present in the pure form as impurity make unwanted products and reduce the productivity of main product and accurate amount of reactants also important for the spontaneous reaction.
Hence, options (a), (b) & (c) are correct.
To know more about percent yield, visit the below link:
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Answer:
pressure and temperature are directly proportional.
Explanation:
At constant temperature and pressure the volume of a gas is directly proportional to the number of moles of gas. Also given a constant temperature and volume the pressure of a gas is directly proportional to the number of moles of gas.
This means that if V is constant then
P = n (RT/V) then n= PV/RT. As P is increased, T is also increased thereby decreasing the value of n since pressure and temperature are directly proportional.
