Answer:
2 only
Explanation:
Electrons are filled in atoms according to the Aufbau principle. Electrons are filled into lower energy orbital before the filling of higher energy orbitals and this sequence must be followed in filling electron orbitals.
The order of arrangement of energy levels may be shown as follows; 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p. This implies that 4f>6s, hence 6s is filled before 4f.
Also, the 6p level > 5d level hence this is the correct option. You must fill the 5d level before you feel the 6p level.
It would still have oceans but no atmospheric water in Earth if no icy debris had arrived.
A. It would still have oceans but no atmospheric water.
<u>Explanation:</u>
Seas characterize our home planet, covering most of the Earth's surface and driving the water cycle that commands our territory and climate. However, progressively significant still, the narrative of our seas wraps our home in a far bigger setting that ventures profound into the universe and spots us in a rich group of sea universes that range our nearby planetary group and past.
It would in any case have seas yet no air water on Earth if no frigid flotsam and jetsam had shown up. For a long time, it was accepted that the frosty moons were only that - solidified husks, strong to their center. However, lately that thought has steadily been supplanted by a fresher, additionally energizing worldview.
Question: Liquids will boil at a higher temperature when they are at a lower elevation true or false ?
Answer: True
Answer : The mass of oxygen formed must be 3.8 grams.
Explanation :
Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
The balanced chemical reaction will be,

According to the law of conservation of mass,
Total mass of reactant side = Total mass of product side
Total mass of
= Total mass of 
As we are given :
The mass of
= 25.3 grams
The mass of
= 23.4 grams
So,



Therefore, the mass of oxygen formed must be 3.8 grams.
I believe the answer is burning a candle