Kerosene was commonly used in lamps because it burns easily. Is this a physical property or a chemical property

In positive numbers less than 1, the zeros between the decimal point and non zero are significant

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid

There are two-speed cameras, one in an are where the speed limit is 30 km/h and another where the speed limit is 50 km/h. in which will there be a smaller time interval between the photographs? explain your answer.