The answer is 3 - convection.
There is not much information given so I would have to make certain assumptions. Here are the following:
1. the gas is ideal
2. The gas is in its standard pressure and specific volume. (1atm and 22.4L/mol)
3. There is no initial temperature hence the pressure given the assumptions above is the "new" pressure.
PV=nRT
P= (<span>0.0821L.atm/mol K)(235)/(22.4L/mol)
P=0.861 atm (below atmospheric pressure) </span>
A measure for the amount of matter in an object would be grams or kilograms.
the measure of the force of gravity acting on an object would be newtons.
the amount of matter in an object is called mass.
the force of gravity acting upon an object would be called weight.
Explanation:
Physical changes are the changes that does not lead to any change in chemical composition of a substance.
For example, mass, density, volume are all physical changes.
On the other hand, a change that leads to formation of a new compound by changing the chemical composition of reactants or combining atoms is known as a chemical change.
For example, combustion, toxicity, reactivity etc are all chemical changes.
Therefore, given changes are identified as follows.
- Coal burning : It is a combustion reaction. Hence, it is a chemical change.
- Ice melting : Physical state of water changes from solid to liquid. Hence, it is a physical change.
- mixing chocolate syrup with milk : No new compound is forming as there is no chemical reaction occurring. Hence, it is also a physical change.
- explosion of a firecracker : It shows reactivity of fire cracker. Hence, it is a chemical reaction.
- magnetizing of a screwdriver : It shows physical attraction between the magnet and screwdriver. Hence, it is a physical change.
If the element have 39 protons, that means that his atomic number is 39, being Yttrium the element. And, the number of protons is the same of the number of electrons, so, 39 electrons.
