The density of Ca will be between that of Mg and Sr
Explanation:
Ca, Mg and Sr are group II elements. They are called alkali earth metals. The correct order of the elements in this group are: Be, Mg, Ca, Sr, Ba and Ra.
Density is an intensive property of matter which describes the amount of matter(mass) per volume of a substance.
- Density varies proportionally with mass. The higher the mass, the higher its density.
- On the periodic table, atomic mass which the number of protons and neutrons in the nucleus of an atom increases down the group.
- This implies a progradation in the value of density down the group. Therefore one expects that the value of density of Ca will fall between that of Mg and Sr. It cannot be more than 2.6g/cm³ nor less than 1.74g/cm³.
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Answer:
2 atm
Explanation:
Chemical reactions are carried out at a certain rate. Sometimes that rate is quite slow, so we want to speed things up, which is usually used by increasing temperature, increasing pressure or adding a catalyst (a substance that increases the rate without changing itself).
If this is the case, then, when writing a chemical equation, we state these special conditions over a right arrow.
Now let's look at the answers:
- 25°C is a value and unit of temperature
- ∆ is a symbol that denotes change
- 2 atm is a value and unit of pressure (atmosphere is old unit for pressure)
- Pt is a chemical symbol for platinum, an element often used as a catalyst.
So, the correct answer is C) 2 atm
Answer:
Explanation:
T1 = 150°C = (150 + 273.15)K = 423.15K
T2 = 45°C = (45 + 273.15)K = 318K
V1 = 693mL = 693cm³
Applying Charle's law, the volume of a given gas is directly proportional to is temperature provided that pressure remains constant.
V = kT
V1 / T1 = V2 / T2
693 / 423.15 = V2 / 318
V2 = (693 * 318) / 423.15 = 520.79cm³
The new volume of the gas is 520.79cm³
Answer:
0.38
Explanation:
Molar mass of thiophene= 84g/mol
Mass of thiophene = 37g
Number of moles= 37/84= 0.44 moles
Molar mass of heptane= 100 g/mol
Mass of heptane = 72g
Number of moles = 72/100= 0.72 moles
Total number of moles= 0.44 + 0.72= 1.16 moles
mole fraction of thiophene = 0.44/1.16= 0.38
Answer: A) Water Explanation: Water molecules are polar molecules