KLNT = Khối lượng của hạt nhân

=> KLNT = 37 amu

=> Nguyên tử x là Chlorine

B

c

\(\dfrac{-13}{15}\) + \(\dfrac{5}{21}\) - \(\dfrac{1}{3}\) - \(\dfrac{2}{15}\) + \(\dfrac{2}{21}\)

=\(\dfrac{-13}{15}\) + \(\dfrac{2}{15}\) - \(\dfrac{5}{21}\) + \(\dfrac{2}{21}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-15}{15}\) + \(\dfrac{7}{21}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-3}{3}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-2}{3}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-3}{3}\)

= -1

=\(\dfrac{14}{13}\) + ( \(\dfrac{-20}{260}\) - \(\dfrac{247}{260}\) )

=\(\dfrac{14}{13}\) + \(\dfrac{-267}{260}\)

=\(\dfrac{280}{260}\) + \(\dfrac{-267}{260}\)

=\(\dfrac{13}{260}\)

=\(\dfrac{1}{20}\)

 

I visit many famous places in Paris last year.

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