Answer : The correct options are,
![-3.50* 10^(4),3.50* 10^(4)\text{ and }3.50* 10^(-4)](https://img.qammunity.org/2019/formulas/chemistry/middle-school/z85ehzv7qypsz5ywuzdyi1pxsu3w9vt46g.png)
Explanation :
Scientific notation : The way or representation of expressing the number that are too big or too small that is written in the decimal form. That means always written in the power of 10 form.
For example : 700 is written in scientific notation as,
![7.0* 10^2](https://img.qammunity.org/2019/formulas/chemistry/middle-school/qo8kbmwe0n5bak9oar6o74uighv1hrtoeh.png)
According to the question,
are written in proper scientific notation. While the other options are not written in proper scientific notation.
Therefore, the correct options are,
![-3.50* 10^(4),3.50* 10^(4)\text{ and }3.50* 10^(-4)](https://img.qammunity.org/2019/formulas/chemistry/middle-school/z85ehzv7qypsz5ywuzdyi1pxsu3w9vt46g.png)