Class 10R sat a test The mean mark for the class was 70% there are 30 students in class 10R, 20 of whom are boys the mean mark for the boys in the test was 62% work out the mean marks for the girls

86

Step-by-step explanation:

Given that there are 30 students in class 10R and the mean marks for the entire class was 70%. Therefore, total mark of class = 70 x 30 = 2100

Given that there are 20 boys in the class and the mean marks for the boys was 62 %. Therefore, total mark of boys = 62 x 20 = 1240

To calculate the mean mark for the girls we need to find the total number of girl and total mark of girls. total number of girl = 30 - 20 (boys) = 10 total mark of girls = total mark of class -  total mark of boys = 2100 - 1240 = 860 mean mark for girls = 860 / 10 = 86

the answer is: d) o, f, and kr.

atomic radius of bromine (br) is 114 pm.

atomic radius of oxygen (o) is 73 pm.

atomic radius of fluorine (f) is 72 pm.

atomic radius of krypron (kr) is 112 pm.

the atomic radius of a chemical element is a measure of the size of its atom.

the atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

the atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.