Answer:
Solids
Explanation:
At standard room temperature and pressure, most of the elements are solids.
Just a few of the elements are liquids and gases at this temperature.
The periodic table is made up of metals, metalloids and non-metals. Most of these substances are actually solid.
Some non-metals are gaseous at standard room temperature.
1. all living things are composed of cells
2. cells are the basic building blocks of life
3. All cells are created by preexisting cells
Answer:
The answer is 1.15m.
Since molality is defined as moles of solute divided by kg of solvent, we need to calculated the moles of H2SO4 and the mass of the solvent, which I presume is water.
We can find the number of H2SO4 moles by using its molarity
C=nV→nH2SO4=C⋅VH2SO4=6.00molesL⋅48.0⋅10−3L=0.288
Since water has a density of 1.00kgL, the mass of solvent is
m=ρ⋅Vwater=1.00kgL⋅0.250L=0.250 kg
Therefore, molality is
m=nmass.solvent=0.288moles0.250kg=1.15m
Answer:
True
Explanation:
The physical changes are reversible in most cases and these changes are not the chemical changes which means that it is only the change in its state not in their nature. Just take the example of water, on cooling it becomes solid and change in color can be seen which is white in solid form and colorless in liquid form. This is also reversible and is a physical change. This means that physical changes can be identified at macroscopic level. Hence the answer is true.
Answer: D.) 25.9%
Explanation:
Dinitrogen pentoxide chemical formular : N2O5
Calculating the molar mass of N2O5
Atomic mass of nitrogen(N) = 14
Atomic mass of oxygen(O) = 16
Therefore molar mass :
N2O5 = (2 × 14) + (5 × 16) = 28 + 80 = 108g/mol
Percentage amount of elements in N205:
NITROGEN (N) :
(Mass of nitrogen / molar mass of N2O5) × 100%
MASS OF NITROGEN = (N2) = 2 × 14 = 28
PERCENT OF NITROGEN : (28/108) × 100%
0.259259 × 100%
= 25.925%
= 25.9%
