咪玩.. 點會變綠- -]
中性 係唔會變色ga(用石蕊的話)-,-
when we'd like to test s/th 's pH value,
we have to use some indicators.
就好似二樓所講 litmus paper 都ok 不過只可以知佢係酸定醶/中性
litmus paper/solutions will turn red in acid and blue in alkali.
litmus papers do not change it's color in neutral.
即係話 如果要用石蕊試紙 test 水 ge ph 值 要test 兩次
1次用藍石蕊試紙(blue litmus paper) 而另1次就用紅石蕊試紙(red litmus paper)
兩次都無變色的話 代表 佢係中性(neutral)
(no observable changes / no color changes)