A physical change is classified as a change that does not affect the identity of the substance. Otherwise, that would be a chemical change. From the picture above, you will know that it is a chemical change if the colored circles combined with a different color. You will know if it's a physical change if there is only separation of the same colors. The answers are shown in the picture attached.
Answer:
Element Helium have<u> 2 energy levels. </u>
Explanation:
<u>HELIUM -</u> With the symbol He and the atomic number 2, helium is a chemical element. It is a colorless , odorless, tasteless, non-toxic, inert, monatomic gas that is the first in the periodic table in the noble gas group. Of all the elements, its boiling point is the lowest.
At about 24 % of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined, it is present. In both the Sun and Jupiter, its abundance is identical to this. This is due to helium-4's very high nuclear binding energy (per nucleon) with respect to the next three elements following helium.
<u>Hence , the answer is 2 energy levels in Helium atom.</u>
Answer:
0.0010m SO₄²⁻
Explanation:
The freezing point depression due the addition of a solute into a pure solvent follows the equation:
ΔT = Kf×m×i (1)
<em>Where ΔT are °C that freezing point decreases (273.15K - 272.47K = 0.68K = 0.68°C). Kf is the constant of freezing point depression (1.86°C/m), m is molality of the solution (0.1778m) and i is Van't Hoff factor.</em>
Van't Hoff factor could be understood as in how many one mole of the solute (sulfuric acid, H₂SO₄), is dissociated.
H₂SO₄ dissociates as follows:
H₂SO₄ → HSO₄⁻ + H⁺
HSO₄⁻ ⇄ SO₄²⁻ + H⁺
<em>Not all HSO₄⁻ dissociates.</em>
1 Mole of H₂SO₄ dissociates in 1 mole of H⁺+ 1 mole of HSO₄⁻ + X moles of SO₄²⁻= 2 + X
Replacing in (1):
0.68°C = 1.86°C/m×0.1778m×i
2.056 = i
Moles of SO₄²⁻ are 2.056 - 2 = 0.056moles SO₄²⁻.
If 1 mole has a concentration of 0.1778m, 0.056moles are:
0.056moles ₓ (0.1778m / 1mole) =
<h3>0.0010m SO₄²⁻</h3>
Answer:
7.5 m/s²
Explanation:
The following data were obtained from the question:
Initial velocity (u) = 21 m/s
Final velocity (v) = 36 m/s
Time (t) = 2 secs
Acceleration (a) =..?
The acceleration of an object is simply defined as the rate of change of velocity of the object with time. Mathematically, it is represented as:
Acceleration (a) = (final velocity (v) – initial velocity (u)) / time (t)
a = (v – u)/t
With the above formula, we can determine the acceleration of the roller coaster as follow:
a = (v – u)/t
a = (36 – 21)/2
a = 15/2
a = 7.5 m/s²
Therefore, the acceleration of the roller coaster is 7.5 m/s².
False. Many theories have been altered over the years due to new information. Scientists usually accept new evidence so they can advance their own research.
