A student carries out a chemical reaction that produces a brown powder. How should the student measure the amount of product formed?
Measure the amount of time it takes for the reaction to happen.
Remove the product from the beaker and use a scale to find its mass.
Measure the length of the powder across the bottom of the beaker.
Record the change in temperature of the beaker.

B

Explanation:

The best way to find out the amount of a substance, especially if you know what it is, is to measure its mass. If the substance is homogenous (even all the way through), then you can determine some other properties of it, such as its volume and number of moles, just by measuring the mass. Hope this helps!

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia