Answer:im in middle school in know this but w x y = d
Explanation:so your answer is d :)
When heat energy is supplied to a material it can raise the temperature of mass of the material.
Specific heat is the amount of energy required by 1 g of material to raise the temperature by 1 °C.
equation is
H = mcΔt
H - heat energy
m - mass of material
c - specific heat of the material
Δt - change in temperature
substituting the values in the equation
120 J = 10 g x c x 5 °C
c = 2.4 Jg⁻¹°C⁻¹
Molar mass of NaHCO3 is 83.9. moles of Na...O3= 5.8/83.9
=0.0691
for every mole of Na..O3 there are 3 O
n(O) = n(NaHCO3) x3
= 0.207
mass of O is the moles x molar mass (16)
therefore the mass of O is 3.3 grams
Answer: e) all of these
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water
, carbon dioxide 
Mixtures are not pure substances as they consist of elements and compounds combined physically and not in any fixed ratio. Example: Air
Thus all given substances are pure substances.