Any mechanical device which is used to help people is a (machine)
the answer is machine
Answer:
(d) burning a log.
(b) toasting a slice of bread;
Explanation:
Chemical change -
A chemical change refers to , the change in which a new compound is formed .
From the question ,
Its is not a chemical process , since no new compound is formed , these is only change in state as the liquid is turning to gaseous sate .
It is not a chemical process , as no new substance is formed .
- toasting a slice of bread
It is a chemical change , in which bread surface is deposited by a brown coat via the process of heating , even this process is a irreversible in nature .
It is a chemical change , as with the help of heating , the wood is turning to ashes .
We will use the formula for freezing point depression :
but first, we need to get the molality m of the solution:
- molality m = moles of C2H5OH / mass of water Kg
when moles of C2H5OH = mass of C2H5OH/ molar mass of C2H5OH
= 11.85 g / 46 g/mol
= 0.258 moles
and when we have the mass of water Kg = 0.368 Kg
so, by substitution on the molality formula:
∴ molality m = 0.258 moles / 0.368 Kg
= 0.7 mol/Kg
and when C2H5OH is a weak acid so, there is no dissociation ∴ i = 1
and when Kf is given = 1.86 C/m
so by substitution on ΔTf formula:
when ΔTf = i Kf m
∴ ΔTf = 1 * 1.86C/m * 0.7mol/Kg
= 1.302 °C
Answer:
Since it is given that the mass of a jelly bean is less than the mass of a gum drop.
So, when we counted out 10 of each kind of candy and measured the mass of each kind of candy, the mass of the jellybeans would be less than the mass of the gumdrops.
This is because mass of jelly bean is less and even if we take take or more jelly beans then also their total mass will remain less than the total mass of same number of gum drops
Explanation:
Hydrogen + oxygen -> water
2H2 + O2 -> 2H2O (balanced)
2 moles of hydrogen gas will react with 1 mole of oxygen to produce 2 moles of water.
following that ratio, 0.734 mole of oxygen must need 0.734 × 2 moles of hydrogen to fully react.
answer is 1.468 moles of hydrogen.
