The center of a circle lies on .

A) every diameter
B) the circle
C) a tangent line
D) every chord

A) every diameter

The center of a circle lies on every diameter.

B) The circle: A circle is a two-dimensional shape where all points are the same distance from the center. So this definition doesn't match the definition of the center of the circle. The center is just a point not several ones.

C) A tangent line: obviously this definition is false. A tangent line is a line not a point.

D) Every chord: A chord is any line segment between two points on a circle. The only chord that passes through is the diameter. So this definition does not include all the chords of a circle

A) Every diameter: This is the correct option! A diameter is any chord that passes through the center.

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.