Questions

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload.

We know that most of the metals are goof conductors of electricity and heat. Metals are very strong but they are malleable i.e, they can be bent into a shape. These are shiny when they are cut or polished. 

Hence, metals are malleable, conductors and luster. All the above are properties of the metals.

The law of conservation of mass states that in any closed system the mass of the system is neither created nor destroyed over time i.e, the mass cannot be changed overtime.

Hence, the given statement is true.

To reduce the risk of bacterial contamination, many foods must be stored in the refrigerator and thus kept below 5 degrees Celsius. These foods are often classified as ‘high-risk foods’ and include – meat, poultry, dairy, seafood, eggs, smallgoods and cooked rice and pasta. This also refers to ready-to-eat foods that have high-risk foods as ingredients and include – casseroles, quiche, pasta salad, pizza, sandwiches and many cakes.

By keeping these high-risk foods under 5 degrees Celsius it stops them from entering the ‘danger-zone’ – temperatures between 5 degrees Celsius and 60 degrees Celsius. The danger-zone is the temperature zone which provides bacteria with the perfect environment to rapidly grow and multiply to numbers that cause food poisoning.

Hong Kong

Here in the option B) H2SO4 - Sulfuric acid is reacting with sodium hydroxide (NaOH), a base to produce a salt (Sodium Sulfate), and water (H2O). This is characteristic of of acid-base neutralization reactions.