Remember this:
atomic mass= atomic number + number of neutrons
The atomic number (same thing as number of protons) in this case is 15. The atomic mass is 31.
So, we subtract 15 from 31 to find the number of neutrons.
31-15=16
16 neutrons!!!
Answer: Melatonin has been used safely for up to 2 years in some people. However, it can cause some side effects including headache, short-term feelings of depression, daytime sleepiness, dizziness, stomach cramps, and irritability. Do not drive or use machinery for four to five hours after taking melatonin.
Answer:
The first option
Explanation:
Carbon is a p-block element. It is the 6th element on the periodic table and therefore it has 6 electrons.
The sub-level notation is given as:
1s² 2s² 2p²
The s-sublevel can only accommodate two maximum electrons because it has one orbital. This is why both 1s and 2s contains just two electrons each. When both sub-levels are filled, we have just 2 remaining electrons to fill the p-sublevel.
The p-sublevel contains 3 orbitals and can accommodate a maximum of 6 electrons. But we have just 2 electrons. According to Hund's rule of maximum mulitiplicity, electrons will go into degenerate orbitals singly before paring up. Therefore, the first two orbitals in p-sublevel will receive an electron each.
This is why the first model fits.
Answer:
C₆H₅COOH Benzoic Acid
Explanation:
Here we are using the extraction method to separate benzoic acid from naphtalene in the ether solution by reacting it with the base sodium bicarbonate to produce the salt sodium benzoate ( naphtalene remains in the organic layer ) .
The sodium benzoate is completely soluble in the aqueous layer being a salt, and reacts with hydrochloric acid ( again an acid base reaction ) which precipitates the benzoic acid since the it is insoluble in water hence separating it.
Answer:
The frequency of photon is 0.75×10¹⁵ s⁻¹.
Explanation:
Given data:
Energy of photon = 5×10⁻¹⁹ J
Frequency of photon = ?
Solution:
Formula;
E = hf
h = planck's constant = 6.63×10⁻³⁴ Js
5×10⁻¹⁹ J = 6.63×10⁻³⁴ Js ×f
f = 5×10⁻¹⁹ J / 6.63×10⁻³⁴ Js
f = 0.75×10¹⁵ s⁻¹
The frequency of photon is 0.75×10¹⁵ s⁻¹.
