Ravi and Tina were working on a project based on ‘Changes around us’, for which they were observing different changes occurring in their daily life. They went to kitchen where they saw their mother was cooking food on LPG stove. Ravi said that burning of LPG in LPG stove involves chemical change. But Tina argued that both physical and chemical changes are involved in this process. According to you who is correct and why?

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

the answer to this question is 3.

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them