Q.Express the following quantities in exponential terms. a. 0.0003498 b. 235.4678 c. 70000.0 d. 1569.00

Scientific (exponential) notation writes any number in the form $N \times 10^n$, where the exponent $n$ is a positive or negative whole number and the coefficient $N$ is restricted to $1 \leq N < 10$. It exists because chemistry regularly involves extremely large numbers (like the roughly $6.022 \times 10^{23}$ molecules in a mole of a substance) and extremely small ones (like the roughly $1.66 \times 10^{-24}$ g mass of a single hydrogen atom), which would be unwieldy and error-prone to write out in full with every zero. To add or subtract numbers in this notation, the numbers must first be rewritten so they share the same exponent, after which only the coefficients are added or subtracted; the shared exponent carries through unchanged to the result. To multiply numbers in this notation, the coefficients are multiplied together and the exponents are added (never multiplied); to divide, the coefficients are divided and the exponents are subtracted. Whenever a calculation produces a coefficient outside the 1–10 range, the decimal point is shifted and the exponent adjusted by a matching amount to bring the answer back into proper scientific-notation form.