Hướng dẫn giải

- Tỉ khối của khí X đối với không khí, với khí $\text{C}{{\text{O}}_{\text{2}}}$ và metan $\text{C}{{\text{H}}_{\text{4}}}$ lần lượt là:

 ${{\text{d}}_{{}^{\text{N}{{\text{O}}_{\text{2}}}}/{}_{\text{kk}}}}\text{=}\frac{{{\text{M}}_{\text{N}{{\text{O}}_{\text{2}}}}}}{{{\text{M}}_{\text{kk}}}}\text{=}\frac{\text{46}}{\text{29}}\text{=1,517}$ .

${{\text{d}}_{{}^{\text{N}{{\text{O}}_{\text{2}}}}/{}_{\text{C}{{\text{O}}_{\text{2}}}}}}\text{=}\frac{{{\text{M}}_{\text{N}{{\text{O}}_{\text{2}}}}}}{{{\text{M}}_{\text{C}{{\text{O}}_{\text{2}}}}}}\text{=}\frac{\text{46}}{\text{44}}\text{=1,045}$

${{\text{d}}_{{}^{\text{N}{{\text{O}}_{\text{2}}}}/{}_{\text{C}{{\text{H}}_{\text{4}}}}}}\text{=}\frac{{{\text{M}}_{\text{N}{{\text{O}}_{\text{2}}}}}}{{{\text{M}}_{\text{C}{{\text{H}}_{\text{4}}}}}}\text{=}\frac{\text{46}}{\text{16}}\text{=2,875}$

Chọn đáp án B.