Which of these characteristics does not apply to cnidarians?

a. are diploblastic
b. possess a gastrovascular cavity with one opening
c. undergo metamorphosis
d. have a central nervous system

These exercises involve the formula for the length of a circular arc. A circular arc of length 25 ft subtends a central angle of

$$50 ^ { \circ }$$

. Find the radius of the circle.

Using cylindrical coordinates, prove that the centroid of a right circular cone of height h and radius R is located at height

$$\frac { h } { 4 }$$

on the central axis.

Draw a Lewis structure for each of the following molecules or ions. Describe the electron-pair geometry and the molecular geometry around the central atom.\

$$NH _2 Cl$$

The area of a sector of a circle and the measure of its central angle are given. Find the radius of the circle. $A=377 \text { in }^{2}, \theta=\frac{5 \pi}{3}$

Find the length to three significant digits of each arc intercepted by a central angle $\theta$ in a circle of radius r. r=15.1 in., $\theta=210^{\circ}$

Prove that the area of a circular sector of radius r with central angle $\theta$ is

$$A=\frac{1}{2} r^{2} \theta,$$

where $\theta$ is measured in radians.

Find the area of a sector of a circle having radius $r$ and central angle $\theta$. See the example in this section.

$$r=18.3 \mathrm{~m}, \theta=125^{\circ}$$

A 320 Newton frictional force acts on the rim of a 1.0 m diameter wheel to oppose its rotational motion. Find the torque about the wheel's central axis.

Find the area of each sector given its central angle $\theta$ and the radius of the circle. Round to the nearest tenth. $\theta=82^{\circ}, r=7.3$

For following, write the Lewis structure(s), predict the molecular structure (including bond angles), and give the expected hybridization of the central atom.

$$\mathrm{SeBr}_4$$

A box contains N identical gas molecules equally divided between its two halves. Does the time spent in the central configuration increase or decrease with an increase in N?

For each data set, find the median, midrange, and geometric mean. (b) Are they reasonable measures of central tendency? Explain.

Exam scores ($9$ students) $\quad 42,55,65,67,68,75,76,78,94$

For following, write the Lewis structure(s), predict the molecular structure (including bond angles), and give the expected hybridization of the central atom.

$$\mathrm{TeF}_6$$