Answer:
True
Explanation:
the machine shown in figure 9.9 is called a wheele and axle. It's a form of lever. the effort arm can rotate in a complete circle, which is the center of the axle.
Answer:
Y, Q, W, Z and X
Y > Q > W > Z > X
Explanation:
To know the most reactive element, the element will be able to displace other metal in it compound. We also have to observe if the reaction occur. If the reaction didn't occur, that means the element is not reactive than the metal found in the other reactant. Invariably their will be no displacement.
Q + w+ Reaction occurs
Q element displace the metal w in it compound . This means Q is more reactive.
x +z+ No reaction
No reaction here. This means x is less reactive than z as it couldn't displace z in it compound.
w + z+ Reaction occurs
w is more reactive than z as it displaces z in it compound.
Q+ + Y Reaction occurs
Y is more reactive than Q as it displaces Q in it compounds.
Therefore, the most reactive to the least reactive is arrange as follows.
Y, Q, W, Z and X
<span>1.58x10^-1 moles
To get the number of moles, we simply need to divide by Avogadro's number, which is 6.0221409x10^23. So
9.50x10^22 / 6.0221409x10^23 = ?
Since we're dealing with scientific notation, we will deal with the significand and exponents separately.
To divide, simply divide the significands as you would normally.
9.50 / 6.0221409 = 1.577512077
And subtract the exponent for the divisor from the exponent from the dividend:
22 - 23 = -1
And we now have
1.577512077 x 10^-1 moles.
But that answer has far too many digits given the precision of the data and should only be as precise as the least precise piece of data used. In this problem, we had 8 digits of precision for Avogadro's number and 3 digits of precision for the number of atoms. Of those 2 pieces of data, 3 is the lowest precision and therefore the answer should be rounded to 3 digits, giving 1.58x10^-1 moles.</span>
Answer:
The density of O₂ gas is 1.71 
Explanation:
Density is a quantity that allows you to measure the amount of mass in a given volume of a substance. So density is defined as the quotient between the mass of a body and the volume it occupies:
An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of the gases:
P * V = n * R * T
So, you can get:
The relationship between number of moles and mass is:
Replacing:
So:
Knowing that 1 mol of O has 16 g, the molar mass of O₂ gas is 32 
.
Then:
In this case you know:
- P=1.27 atm
- molar mass of O₂= 32 .
- R= 0.0821
- T= 16 °C= 289 °K (0°C= 273°K)
Replacing:
Solving:
density= 1.71
<u><em>The density of O₂ gas is 1.71 </em></u><u><em></em></u>
Answer: A) H-H is least polar
Explanation:
Electronegativity is defined as the property of an element to attract a shared pair of electron towards itself. The more is the difference in electronegativity, the more polat the bond is.
1. H-H : Electronegativity difference = electronegativity of hydrogen - electronegativity of hydrogen =2.1 -2.1= 0
2. H-Cl : Electronegativity difference = electronegativity of chlorine - electronegativity of hydrogen = 3-2.1 = 0.9
3. H-F : Electronegativity difference = electronegativity of fluorine - electronegativity of hydrogen= 4-2.1= 1.9
4. H-I : Electronegativity difference = electronegativity of iodine - electronegativity of hydrogen= 2.5 -2.1= 0.4
Thus the least electronegativity difference between the bonded atoms is in H-H , this is least polar.
