The strength of an electromagnet increases with

Which of the following will increase the boiling point of water?

I. Taking it to a high altitude
II. Dissolving a salt into it
III. Heating it in a sealed flask
IV. Increasing the rate of heat supply

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Transformers are designed so that energy losses are reduced to a minimum. This is achieved through which of these process?

I. Using a soft iron ore
II. Laminating the iron core to reduce energy loses due to eddy current
III. Designing an efficient iron core