<u>Answer:</u> The mass of plastic sheet is 
<u>Explanation:</u>
The plastic sheet is in the form of cuboid. To calculate the volume of cuboid, we use the equation:

where,
V = volume of cuboid
l = length of cuboid = 10.0 m = 1000 cm (Conversion factor: 1 m = 100 cm)
b = breadth of cuboid = 1.0 m = 100 cm
h = height of cuboid = 1 cm
Putting values in above equation, we get:

To calculate mass of a substance, we use the equation:
We are given:
Density of plastic sheet = 
Volume of plastic sheet = 
Putting values in equation 1, we get:

Hence, the mass of plastic sheet is 
Answer:
A) at the rod's geometrical center
Explanation:
Let us assume that the rod is replaced by water. And now this water volume is in translational and in rotational equilibrium.
Therefore, a net upward force must have been exerted by the surrounding liquid which acts at the center of mass of the water volume.
This force determines through the geometric center of the column of the cylindrical water
Moreover, the force is also independent of submerged body into it
Hence, the first option is correct
Which ones do you need help on?
Answer:

Explanation:
The reaction is a precipitation reaction. In other words, the two aqueous solutions react to give the solid salt, potassium chloride (KCl) in this case.

Because the reaction product is a solid, the net ionic equation can be written as:

This is the resultant equation after removing spectator ions: sulfate and strontium.