Answer:
Krypton
Explanation:
When Selenium forms an ion, it is trying to become krypton which is a noble gas.
Selenium belongs to the oxygen group on the periodic table. In this group, the atoms prefers to gain two electrons to complete their octet. When selenium gains two electrons, its octet is complete.
This will make the atom resemble krypton on the periodic table of elements.
This structure which is an octet confers a special stability on the element.
Answer: when two elements combine, A and B, the ratio of the weight of B combining with A is always a whole number
Explanation:
Answer: 69.72 kg of cryolite will be produced.
Explanation:
The balanced chemical equation is:
To calculate the moles, we use the equation:
moles of 
= 
moles of 
= 
moles of 
= 
As 1 mole of reacts with 6 moles of
166 moles of reacts with = 
moles of
As 1 mole of reacts with 12 moles of
166 moles of reacts with = 
moles of
Thus is the limiting reagent.
As 1 mole of produces = 2 moles of cryolite
166 moles of reacts with = 
moles of cryolite
Mass of cryolite 
= 
Thus 69.72 kg of cryolite will be produced.
Answer:
This is the balanced equation:
Pb(NO₃)₂ (aq) + 2NaI (aq) → 2NaNO₃ (aq) + PbI₂ (s) ↓
Explanation:
This are the reactants:
PbNO₃
NaI
Iodide can react to Pb²⁺ to make a solid compound.
