What is the standard notation for 7.934 x 10-4 ?

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

Achemistry student weighs out 0.306 g of citric acid (h3c6h5o7), a triprotic acid, into a 250 ml volumetric flask and dilutes to the mark with distilled water. he plans to titrate the acid with 0.1000 m naoh solution. calculate the volume of naoh solution the student will need to add to reach the final equivalence point. be sure your answer has the correct number of significant digits.

Convert .347 kilometers to miles show your work