Answer:
We are asked to describe the half-life of the radioactive materials.
- Hence the 3rd option is correct
The correct answer among the choices is the last option. <span>Green light has a higher frequency than orange light. Frequency is inversely proportional to wavelength. G</span>reen has wavelengths ranging form 495 to 570 nm and orange has wavelengths ranging from 590 to 620 nm. Speed is said to be directly proportional with wavelength. Higher wavelength means more faster light.
Magnesium has atomic no 12
Electronic configuration given by
Or
Answer:
4Fe + 3O₂ → 2Fe₂O₃
Explanation:
Fe → ²⁺
O → ²⁻
But Iron III is Fe³⁺
So we have Fe³⁺ and O²⁻, the formula for the oxide must be Fe₂O₃ so the equation can be:
4Fe + 3O₂ → 2Fe₂O₃
Answer:

Explanation:
To convert from moles to grams, the molar mass must be used.
1. Find Molar Mass
The compound is iron (III) chloride: FeCl₃
First, find the molar masses of the individual elements in the compound: iron (Fe) and chlorine (Cl).
There are 3 atoms of chlorine, denoted by the subscript after Cl. Multiply the molar mass of chlorine by 3 and add iron's molar mass.
- FeCl₃: 3(35.45 g/mol)+(55.84 g/mol)=162.19 g/mol
This number tells us the grams of FeCl₃ in 1 mole.
2. Calculate Moles
Use the number as a ratio.

Multiply by the given number of grams, 345.0.

Flip the fraction so the grams of FeCl₃ will cancel.



Divide.

3. Round
The original measurement of grams, 345.0, has 4 significant figures. We must round our answer to 4 sig figs.
For the answer we calculated, that is the thousandth place.
The 1 in the ten thousandth place tells us to leave the 7 in the thousandth place.

There are about <u>2.127 mole</u>s of iron (III) chloride in 345.0 grams.