Answer:
Cool air moves down while hot air rises
Answer:
Place 20.0 g NaOH(s) in a flask and dilute to 1.00 L with water.
Explanation:
Answer:
Molar mass = 30.026 g/mol
Explanation:
Let Molar mass be mm
mm of CH2O = 12.01 + 2(1.008) + 16.00
= 12.01 + 2.016 + 16.00 = 30.026 g/mol
The mass of impure
is 20.7167 g. The decomposition reaction is as follows:

Here, 1 mole of
gives 1 mole of MgO.
Molar mass of
and MgO is 84.31 g/mol and 40.3044 g/mol respectively.
Converting number of moles in terms of mass,

Here, M is molar mass.
Since, 
Thus, 
On putting the values,

Rearranging,

Or,
...... (1)
Let the mass of impurity be
and mass of impure
is 20.7167 g thus,
...... (2)
Also, mass of impure MgO is 16.8817 g thus,
...... (3)
On comparing equations (2) and (3),

Putting the value of
in equation (1),

Or,

Or,

Or,

Or,

Thus, magnesium carbonate present in the original sample is 7.35 g.
<span>Cracking of hydrocarbons involves thermal decomposition.
This means that large hydrocarbon molecules break into
smaller molecules when they are heated. The <span>hydrocarbons
</span>are boiled and the <span>hydrocarbon gases </span>are either
mixed with steam and heated to a very high temperature or
passed over a hot <span>powdered </span>aluminium oxide catalyst.
The catalyst works by providing the <span>hydrocarbon gases
</span>with a convenient surface for the cracking to take place.</span>
<span>For example, decane (an alkane with 10 carbons)
can be cracked to produce octane and ethene.</span>
decane<span> octane + ethene.
<span>C10H22</span>(g) <span>C8H18</span>(g) + C2<span>H4</span>(g)</span>
<span>Octane is used as petrol.
Ethene is used in the manufacture of polymers.</span>
<span>Cracking an alkane produces a smaller alkane plus an alkene.
If you add up the number of hydrogen atoms in the
above reaction, you will see that there are 22 on each side.
An alkene is produced because the original alkane does
<span>not </span>have enough hydrogen atoms to produce two more<span> alkanes</span>.</span>
<span>
</span>
<span>hope this helps </span>