Which of the following blood vessels can regulate the amount of blood flow to a certain organ?
A. aorta
B. arterioles
C. veins
D. capillaries
拜託加埋explain >_< ( 可以用中文 但係 科學名詞用返 英文)
CHEMISTRY
1) atom , molecule , element, ion ,compound 有咩分別?
2) covalent bond , metallic bond , ionic bond , dative covalent bond 可以點分?
3) 點樣先知道D ion既 charged去令到個 element/compound變 stable??
4) 點樣balance 1條式??
5) anion 同 cation 係形容咩野?作者: -終場ソ使者- 時間: 26-1-2010 23:24 本帖最後由 -終場ソ使者- 於 26-1-2010 23:26 編輯
1)
Atom is a particle who contains protons,neutrons and electrons.
An ion forms when an atom loses or gains one or more electrons.It contains positively or negatively charged.
Elements are substances which cannot be broken down into simpler by chemical means.
Compound are substances composed of two or more elements.
Molecule is a particle who made up of non-metals and non-metals.
2)
Covalent bond---Is a bond between non-metals and non-metals.
Metallic bond---Is a bond between metals and metals by a "sea" of mobile electrons.
Ionic bond---Is a bond between metals and non-metals
Dative covalent bond---Is a bond in which the bond pair electrons are provided by anyother atom.
3)
???
4)
Brain used.
e.g. C[sub]3[/sub]H[sub]8[/sub]+O[sub]2[/sub]-->H[sub]2[/sub]O+CO[sub]2[/sub]
5)
Anion---An ion who is positive.
Cation---An ion who is negative.作者: [S]【YU】 時間: 27-1-2010 00:16
印象中...
只係有d definitions 執得靚d 係保障自己既做法我相信你一定理解:]作者: paladin 時間: 9-11-2011 20:10
arterioles
as they are one of the sole target for vasodilation/vasoconstriction aided by muscle contraction.