Order Of Magnitude

As covered in NCERT Class 11, Chapter 2 (Units and Measurements), the order of magnitude is the power of ten nearest to a quantity when written in standard scientific notation, obtained by rounding the leading coefficient. One angstrom equals 10^{-10} m, so 1.06 angstrom equals 1.06 × 10^{-10} m. Since the coefficient 1.06 is less than the rounding threshold of about 3.16, it rounds down to 1, leaving the order of magnitude as 10^{-10}. The option 10^{-9} is wrong because that corresponds to a nanometre, ten times larger than an angstrom. The option 10^{-11} is wrong as it would require a coefficient below one tenth of an angstrom. The option 10^{-8} is wrong since it overestimates the atomic size by a hundredfold. A sanity check confirms that atomic dimensions are universally quoted on the angstrom scale, which is exactly 10^{-10} m, matching the chosen answer.