Back in their laboratory, the team of scientists carefully measure the changes in the density of a freshwater sample as they decrease its temperature from 20°C to 0°C. Based on the data in the table, what effect does decrease the temperature from 20°C to 4°C have on the sample’s density? Temperature (°C) Density (kg/m3)
20 998.2071
19 998.4082
18 998.5986
17 998.7779
16 998.946
15 999.1026
14 999.2474
13 999.3801
12 999.5004
11 999.6018
10 999.7026
9 999.7838
8 999.8512
7 999.9045
6 999.9432
5 999.9668
4 999.975
3 999.9672
2 999.9429
1 999.9015
0 (ice forms) 999.9015

h let me think

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

one negative thing it that it can kill water animals. another negative thing is it can cause the destruction of ecosystem. one way water pollution can be reduced is to conserve energy.