1 — Element D and A ( Which are Sodium and aluminium )
2 — ( 2 + 8 + 3 = 13 electrons total ) Element A Because it's atomic number is 13.
3 — Element E Is stable. ( Which is Argon )
( Note, Elements which has 8 election on its outermost cell is stable. ( Helium is exception which is a noble gas but have 2 electrons in outermost cell )
4 — Element F , which is hydrogen. ( Hydrogen is the only element to not have any neutron )
5 — Element D ( Which is sodium )
6 — The element F ( Which is hydrogen ) Don't contain any neutron.
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Zn + H₂SO₄ = ZnSO₄ + H₂
answer (3) <span>single replacement
hope this helps!</span>
A solid will always hold its shape as long as there are no item/forces acting on it.
Liquids, plasma, and gases will never hold a shape on there own, mostly all liquids only hold the shape there given. Gases never really have a shape.And plasma is a form of energy, so its more like the gas, it has to be given a shape/container.
Answer :B
Hope this helps
Answer: 
Explanation:
Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and 
for the reaction comes out to be negative.
Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and for the reaction comes out to be positive.
As the heat is absorbed the reactants , the reaction is endothermic and for the given endothermic reaction will be +127 KJ
Answer:
Explanation:
The reactivity of elements in the periodic table is based on the number of electrons in there outermost shell. Elements (metals) that have few electrons in there outermost shell are highly reactive because it is easier to lose fewer number of electrons (in the outermost shell during a reaction) than to lose more electrons in the outermost shell - thus metals that have one electron in there outermost shell are most reactive and are more reactive than those that have two electrons in there outermost shell. Hence, metals in group 1 are the most reactive metals because they all have one electron in there outermost shell.
Non-metals that have fewer electrons to complete there octet configuration are highly reactive because it is easier to gain fewer number of electrons (in the outermost shell during a reaction) than to gain more number of electrons - thus nonmetals that have seven electrons in there outermost shell are more reactive than nonmetals that have six electrons in there outermost shell. Hence, nonmetals in group 17 are the most reactive nonmetals because they contain seven electrons and have just one electron left to complete there octet configuration.
