Light absorbed by objects, enters the eyes, and is refracted by the optic nerve in the retina.
B.
Light reflects off objects, enters the eyes, and is detected by the optic nerve in the retina.
C.
Light refracts off objects, enters the eyes, and is captured as a photograph by the lenses.
D.
Light reflects off objects, enters the eyes, and is detected by light-sensitive cells in the retina.
The human eye see objects through light reflects off objects, enters the eyes, and is detected by the optic nerve in the retina. The answer is letter B. The rest of the choices do not answer the question above.
(2) reduction (4) nuclear fusion
Answer:
Nuclear Fusion
Explanation:
In nuclear fusion two lighter nuclei combine together in order to form one heavier nucleus.
For example, the energy generated from the Sun is made by nuclear fusion: Two hydrogen (H, atomic number 1) nuclei combine in order to form one helium (He, atomic number 2) nucleus.
Nuclear fission is the opposite reaction, in which one heavier nucleus splits into two lighter nuclei.
Explanation:
Let's consider sulphate radical, the chemical formula is given by SO42−. Here we can see there is a -2 charge on SO4, which means it has -2 valency. Now look at the option (a), phosphate can be written as PO43−. There is -3 charge on PO4, that means it has -3 valency.
Explanation:
molecular formula of sulphate ion is SO₄²⁻
and
the valency of sulphate ion is 2.
Answer: 7.8 moles of NaCl result from the complete reaction of 3.9 mol of
Explanation:
To calculate the moles :
As is the excess reagent, is the limiting reagent as it limits the formation of product.
According to stoichiometry :
1 mole of gives = 2 moles of
Thus 3.9 moles of will give= of
7.8 moles of NaCl result from the complete reaction of 3.9 mol of
Answer:
The correct option is: Potassium
Explanation:
Sodium, Potassium, Rubidium and Caesium are referred to as the alkali metals that belong to the group 1 of the periodic table, thus having one valence electron in their outer or valence shell.
Sodium, atomic number 11, belongs to the period 3 of the periodic table. It has three shells and the number of electrons per shell is 2, 8, 1.
Potassium, atomic number 19, belongs to the period 4 of the periodic table. It has four shells and the number of electrons per shell is 2, 8, 8, 1.
Rubidium, atomic number 37, belongs to the period 5 of the periodic table. It has five shells and the number of electrons per shell is 2, 8, 18, 8, 1.
Caesium, atomic number 37, belongs to the period 6 of the periodic table. It has six shells and the number of electrons per shell is 2, 8, 18, 18, 8, 1.
Therefore, Potassium, atomic number 19, has four shells or energy levels.
Among the given options, the element that has four energy levels is potassium (K). The correct answer is option 2.
An energy level is a specific amount of energy that an electron in an atom can possess.
The electronic configurations of Na (sodium), K (potassium), Cs (cesium), and Rb (rubidium) are as follows:
Na:
K:
Cs:
Rb:
The above electronic configurations shows that only Potassium has 4 energy levels while Na has 3 energy levels, Cs has 6 energy levels and Rb has 5 energy levels.
Therefore, the correct answer is option 2. Potassium (K) has four energy levels.
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(3) from 400.oC to 200.oC
(4) from 200.oC to 400.oC