Answer:
Both <u>elements </u>and <u>compounds</u> can be classifies as pure substances because they have distinct properties and composition.
Explanation:
Elements and compounds are considered as pure substances because both are always formed form are have same kind of atoms.
For example,
Carbon dioxide is compound. It always consist of one carbon atom and two oxygen atoms.
Water is compound it always have same kind of atoms two hydrogen and one oxygen that's why compounds are considered as pure substances.
Same is the case with elements. For example,
Hydrogen is element and it always consist of H atoms.
Iron is another element and it always have iron atoms.
So elements and compounds are always consist of same substances that's why they are considered as pure.
Rutherford, Geiger and Marsden's experiment proved that every atom has a nucleus and that this nucleus is of positive charge and contains the most of the mass of the atom. 0.005% of the volume occupied by the electrons is the volume of the nucleus.
Answer:(4) ----accepts a proton
Explanation:
H2O water can produce both hydrogen and hydroxide ions
H2O --> H+ + OH-
According to the Bronsted-Lowry theory, it can be a proton donor and a proton acceptor.this means that It can donate a hydrogen ion to become its conjugate base, or can accept a hydrogen ion to form its conjugate acid,
When , a water molecule, H2O accepts a proton it will act as a Brønsted-Lowry base especially when dissolved in a strong acidic medium. for eg
HCl + H2O(l) → H3O+(aq) + Cl−(aq)
Here, Hydrochloric acid is a strong acid and ionizes completely in water, since it is more acidic than water, the water will act as a base.
Answer:
The total amount of heat released is 68.7 kJ
Explanation:
Given that:
mass of water = 94.0 g
moles of water = 94 / 18.02 = 5.216
80⁰C ------> 0⁰C --------> -30⁰C
Q1 = m Cp dT
= 94 x 4.184 x (0 - 80)
= -31463.68 J
= -31.43 kJ
Q2 = 6.01 x 10^3 x 5.216
= - 31348.16 J
= -31.35 kJ
Q3 = - 94 x 2.09 x 30
= - 5893.8 J
= -5.894 kJ
Total heat = Q1 + Q2 + Q3 = -31.43 kJ + (-31.35 kJ ) + (-5.894 kJ
) = -68.7 kJ
Total heat released = -68.7 kJ
Note that the "negative sign" simply indicates heat released, therefore no need to put it in the answer.
Answer:
He concluded that atoms contain small negatively charged particles that are called electrons.
