Change happen to happened because it is past tense
I can’t so many vacancies for you you’re my brother and I’m gonna try to get him to answer this crazyAbout to leave this world to see if he wants to answer and see if I can help you with this
Explanation:
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Here are possible changes that could take place if the concentration of oxygen in theatmosphere were halved:1.Iron and steel would rust more slowly, prolonging the useful life of many objects madefrom these materials.2.Fires would burn less vigorously and produce more CO and soot. Logs in your fireplacemight last longer.3.Your body can adapt (just as it does at higher elevations) to lower levels of oxygen. But inthis case, the level may be too low for metabolic processes involving oxygen to occur at fastenough rates for life as we currently know it.33.Explain why CO is called the “silent killer.” Select two other pollutants for which this namewould not apply and explain why not.Answer:CO is termed the “silent killer” because your senses cannot detect this colorless, tasteless,and odorless gas. The same term cannot be applied to pollutants such as O3or SO2becauseeach has a distinctive odor that can be detected at concentrations below the level of toxicity.34.Cigarette smoke is 2–3% carbon monoxide.a.How many parts per million is this?b.How does this value compare with the National Ambient Air Quality Standards for CO inboth a 1-hour and an 8-hour period?c.Propose a reason why smokers do not succumb to carbon monoxide poisoning.Answer:a. To convert from percent to ppm, move the decimal point 4 places to the right.Alternatively:3%=3pph3pph×1,000,000ppm100pph=30,000ppmb.The NAAQS for CO in an 8-hour period is 9 ppm. The concentration of CO in cigarettesmoke is over three thousand times the 8-hour standard. The NAAS for CO
