Answer:
The physical and chemical properties of the product do not match the properties of the reactant.
Explanation:
Chemical change:
The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.
These changes are irreversible
These changes occur due to chemical reactions
These may not be observed with naked eye
Example:
Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood
Boiling of egg: that change the chemical composition of protein in the egg .
The reaction of Hydrogen and oxygen:
H 2 (g) + O 2 (g) -------------------------------------> 2H 2O (l)
The reaction between sugar and oxygen form a product which is different from the reactant that's why it indicate the occurrence of chemical reaction.
While in case of physical changes just state of matter are changed. Properties remain same.
Aluminum is an example of an element
Answer:
2.1077×10^25 atoms
Explanation:
Since one molecule of K2SO4 contains 7 atoms {Two Potassium(K), One Sulphur (S) and Four Oxygen (O)}.
Thus in 5 moles there will be,
6.022 × 10²³ × 7 × 5 =
210.77 × 10²³ or 2.1077 × 10²⁵ or 21077 × 10²¹ atoms.
Here, 6.022 × 10²³ is the Avogadro number.
Explanation:
It is known that relation between heat energy and temperature change is as follows.
Q =
where, q = heat energy
m = mass of the solution or solvent
= change in temperature
Hence, putting the given values into the above formula as follows.
Q =
=
= 34650 J
Now, calculate the energy of photons at wavelength 3.02 mm as follows.
E =
where, h = planks constant =
c = velocity of light = m/s
= wavelength = 3.02 mm = m (as 1 m = 1000 mm)
Therefore, putting the given values into the above formula as follows.
E =
=
= J
Now, the number of photons required of energy J/photon for the total energy of 34650 J as follows.
n =
=
= photons
or, = photons
Thus, we can conclude that the minimum number of photons present are .
Yes because he presumably wrote the procedure while his assistants just did grunt work