Physical changes only affect the appearance of an object. While chemical happens to the chemical make up and cannot be reversed. Think of it this way- physical change is like hair tint , it wears off- chemical is like permanent hair dye, it's permanent.
Answer:
Precision is good but accuracy is poor
Explanation:
The precision in a measure is about how close is a measured value to each other. In the problem, all measurements are between 15.33 and 15.34cm. Thus, you can say precision is good
And accuracy is about how close are the measured values to the theoretical or real value. The real length of the pencil is 15.85cm. The measurements are not even close of the real value. For that reason, you can sat accuracy of the measurements is poor.
Answer:
Boron family.
Explanation:
Group 13 is called boron family.
It consist of five members boron, aluminum, gallium, indium and thallium.
Boron is semi metal while other members are metals.
Boron hydrates are used to make organic compounds.
Al is soft metal and aluminum oxides are widely used as thermal insulator.
Aluminum sulfate is also very important commercial compound used in sizing paper.
Gallium is also very important element of this group. It form gallium arsenide which is used to convert the light into electricity.
Indium is malleable soft metal which is used in optical instruments.
Thallium is highly toxic and for the long period of time it as used as insect killing poison.
