【问题】：大家好!我想请教一下三题的原文问题，麻烦请大家帮我解答，感恩 (1)A salamander relies on hydrogen bonding to stick to various surfaces. Therefore, a salamander would have the greatest difficulty clinging to a ____ a)slightly damp surface b)surface of hydrocarbons c)surface of mostly carbon-oxygen bonds d)sruface of mostly carbon-nitrogen bonds ans:b 个人看法:这题是指van der walls forces中的氢键吗？如是，那为何不是"a"？感恩 (2)An atom has four electrons in its valence shell.What types of covalent bonds is it capable of forming a)single,bouble, or triple b)single and double only c)single bonds only d)double bonds only ans:a 个人看法:可以举例形成triple bond的元素吗？感恩!(因我找不到><"") (3)Nitrogen(N)normally forms three covalent bonds with a valence of 5.However, ammonium has four covalent bonds,each to a different hydrogen(H)atom(H has a valence of 1).What do you predict to be the charge on ammonium？ a)+1 b)-1 c)+2 d)-2 ans:a 个人看法:这题Nitrogen不是只能与Hydrogen形成三个共价键？就算形成四个共价键，那 就不是多拿了一个电子，所以应该是-1，怎麽会是+1呢？烦请赐教，感恩! --

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