How can eclipsing binary stars be identified? they are brighter than any single stars. they are cool red stars. they are all white dwarfs. they become dimmer at regular intervals.

0.051kg

Explanation:

Using the law of calorimetry which states that the amount of heat lost by a hot substance is equal to the amount of heat gained by the cold substance.

Applying the law to this question,

Amount of heat lost by the heater = heat gained by the water

Heat lost by Immersion heater Q1 = Power×time

Given power = 500W time = 2minutes = 120seconds

Heat loss by immersion heater = 500×120 = 60,000Joules

Heat gained by water = mc∆t where;

m is the mass of the water in the bowl = ?

c is the specific heat capacity = 4.2x10³JK-1 Kg-1

∆t = change in temperature = 90°C -85°C = 5°C

= 273+5 = 278K

Substituting in the formula we have;

Q2= 4.2×10³×278×m = 1,167,600m

According to the law if calorimetry,

Q2=Q1

1,167,600m = 60000

m = 60000/1,167,600

m = 0.051kg

Therefore the mass of water in the bowl is 0.051kg