Answer:
28
Explanation:
Velocity ratio= Radius of wheel/radius of axle
Radius of wheel= 4.125 inches
Radius of axle= 0.125 inches
Velocity ratio = 4.125/0.125 = 33
Then;
Efficiency = mechanical advantage/velocity ratio × 100
Since the efficiency of the system = 85%
85 = mechanical advantage/33 × 100
Mechanical advantage = 85 × 33/100 = 28
The correct option should be ultrasound technology (option B) because it is related to sonographers or ultrasound technicians. they are most likely with while pregnancy but they have plenty of uses, such as evaluating and diagnosis, many medical treatment for elderly patients.
D is a correct Lewis Dot structure. Nitrogen has 4 valence electrons.
Answer:
The freezing point will be 
Explanation:
The depression in freezing point is a colligative property.
It is related to molality as:
Where
Kf= 
the molality is calculated as:
Depression in freezing point = 
The new freezing point = 
We have to know the number of Na⁺ ions in the unit cell.
The number of Na⁺ ions in the unit cell is (D) 8.
Sodium oxide (Na2O) crystallizes in a structure in which the O2– ions are in a face - centered cubic lattice and the Na+ ions are in tetrahedral holes.
O²⁻ ions are in a face centred cubic lattice, so the number of O²⁻ ions per unit cell is equal to 4. The number of tetrahedral hole= 2 X 4=8. Na+ ions are present in tetrahedral holes, which indicates there are 8 number of Na+ ions in the unit cell.
