Answer:
Gasoline
Explanation:
Pure Substance: are those having same type of atoms or molecules.
Compound: one or more atoms of the element combine to form a compound.
Mixture: is combination of one or more substances mix together.
Homogeneous Mixture: are those which are not distinguish by naked eye but can be separated into its components by physical means
Heterogeneous mixture: are those which can be distinguishing by naked eye and can be separated into its components by physical means.
So keeping in mind the above definitions
Table salt:
The chemical formula of table salt is NaCl and it a pure compound not mixture.
Gasoline:
Gasoline is mixture of hydrocarbon, It contains small hydrocarbons ranging from 4 Carbon to 12 Carbon per molecule. it is a homogeneous mixture.
Aluminum:
Aluminum is a pure substance that is made up of same kind of atoms. so it is an element and not mixture. Its symbol is Al
Carbon dioxide:
Carbon dioxide is a pure compound and its chemical formula is CO₂ and not a mixture.
So, the write option is Gasoline.
Answer:
Molarity = 0.3 M
Explanation:
Given data:
Moles of NaOH = 0.720 mol
Volume of water = 2.40 L
Molarity = ?
Solution:
Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.
Formula:
Molarity = number of moles of solute / L of solution
Molarity = 0.720 mol / 2.40 L
Molarity = 0.3 mol/L
Molarity = 0.3 M
Answer:
The number of valence electrons can be known from the group that the element is in (except the lanthanides, actinides and groups 3-12).
Explanation:
Group 1 has 1 valence electron. Group 2 has 2 valence electrons. Group 13 has 3 valence electrons. Group 14 has 4, group 15 has 5, group 16 has 6, group 17 has 7, and group 18 has 8.
Group 18 are the noble gases which are stable.
Group 17 are the halogens and react well with the alkali metals.
The volume of nitrogen monoxide that occupy at STP is= 277 Ml
calculation
The volume is obtained using the combined gas law that is P1V1/T1= P2V2?
Where P1 = 720 MmHg
V1 = 400ml
T1= 100 +273= 373 K
At STP temperature = 273 K and pressure= 760 mm hg
therefore T2= 273 k
p2 = 760 mmhg
V2=?
make V2 the subject of the formula
V2= (T2 ×P1 ×V1)/(P2×T1)
V2 is therefore = (273k x720 mmhg x 400 ml)/(760 mmhg x373K) = 277 Ml
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1. Remember (sum of products) - (sum of reactants)
So ΔHrxn = 2 ΔHf [H2(g)] + ΔHf [Ca(OH)2(s)] - 2 ΔHf [H2O(l)] - ΔHf [Ca(s)]
= 2*0 + -986.09 kJ/mol - 2*(-285.8 kJ/mol) - 0
Do the math and you'll have the answer. BTW the ΔHf [H2(g)] and ΔHf
[Ca(s)] were 0 because these are elements in their standard states.
</span>HOPE THIS HELPS ;)
