Why are these details about Rolf's childhood important?

Explain how learned helplessness can develop in childhood.

Carissa's Fashions sold $138$ jackets at a loss of $\$7 (-\$7)$ each. What was her total loss?

An astronomer observes several stars and records their respective colours, as shown in Table below. Using this data, order the stars by temperature from warmest to coolest.

$$\begin{matrix} \text{Star} & \text{Colour}\\ \text{10 Lacertra} & \text{bluish}\\ \text{Antares} & \text{reddish}\\ \text{Aldebaran} & \text{orange-ish}\\ \text{Canopus} & \text{bluish white}\\ \end{matrix}$$

Complete the fallowing sentences by choosing the word that best completes the specified relationship. Some word pairs will be antonyms, some will be synonyms, and some will be words often used in the same context.

Replenish is closest in meaning to

A. retort.

B. rail.

C. fret.

D . deploy.

E. bolster.

Explain why the $Na^+$ and $K^+$ transports were unaffected by the addition of glucose.

(a) Interpret: Why does the speaker call his childhood in Carrick an "interlude"?
(b) Draw Conclusions: How is MacNeice's identity, as described in this poem, influenced by two cultures but separate from both?

a. How many stereoisomers are acquired from the reaction of 2-pentanone with ethylmagnesium bromide followed by the addition of dilute acid?

b. How many stereoisomers are acquired from the reaction of 2-pentanone with methylmagnesium bromide followed by the addition of dilute acid?

Carry out the indicated operation, or explain why it cannot be performed.

Let

$$C=\begin{bmatrix} \frac12 & 3\\ 2 & \frac32\\ -2 & 1 \end{bmatrix}$$

$$D=\begin{bmatrix} 1 & 4\\ 0 & -1\\ 2 & 0 \end{bmatrix}$$

2C + 3D

What characteristics of early Homo sapiens most set them apart from earlier hominids?

Let G be a connected graph in which every pair of edges have an endpoint in common. Show that G is either a star or a $K_3$.

Would you expect to find an earthlike planet (with a solid surface) around a very low-mass star that formed right at the beginning of a globular cluster’s life? Explain.

In the space provided, write the letter of the choice that is most nearly the same in meaning as the given word.

predilection

A. a fear

B. a liking

C. a mistake

D. a loss

The text explains that massive stars have shorter lifetimes than low-mass stars. Even though massive stars have more fuel to burn, they use it up faster than low-mass stars. You can check and see whether this statement is true. The lifetime of a star is directly proportional to the amount of mass (fuel) it contains and inversely proportional to the rate at which it uses up that fuel (i.e., to its luminosity). Since the lifetime of the Sun is about $10^{10}$ y, we have the following relationship: $T=10^{10} \frac{M}{L} \mathrm{y}$ where T is the lifetime of a main-sequence star, M is its mass measured in terms of the mass of the Sun, and L is its luminosity measured in terms of the Sun’s luminosity. A. Explain in words why this equation works. B. Use the data in Table to calculate the ages of the main-sequence stars listed.

$$\begin{matrix} \text{Caracteristics of Main-Sequence Stars}\\ \text{Spectral Type} & \text{Mass (Sun=1)} & \text{Luminosity (Sun=1)} & \text{Temperature} & \text{Radius (Sun=1)}\\ \text{O5} & \text{40} & \text{7}{ \times 10^{5}} & \text{40,000 K} & \text{18}\\ \text{B0} & \text{16} & \text{2.7}{ \times 10^{5}} & \text{28,000 K} & \text{7}\\ \text{A0} & \text{3.3} & \text{55} & \text{10,000 K} & \text{2.5}\\ \text{F0} & \text{1.7} & \text{5} & \text{7500 K} & \text{1.4}\\ \text{G0} & \text{1.1} & \text{1.4} & \text{6000 K} & \text{1.1}\\ \text{K0} & \text{0.8} & \text{0.35} & \text{5000 K} & \text{0.8}\\ \text{M0} & \text{0.4} & \text{0.05} & \text{3500 K} & \text{0.6}\\ \end{matrix}$$

C. Do low-mass stars have longer main-sequence lifetimes? D. Do you get the same answers as those in Table?

$$\begin{matrix} \text{Lifetimes of Main-Sequence Stars}\\ \text{Spectral Type} & \text{Surface Temperature (K)} & \text{Mass (Mass of Sun=1)} & \text{Lifetime od Main Sequence (years)}\\ \text{O5} & \text{54000} & \text{40} & \text{1 million}\\ \text{B0} & \text{29200} & \text{16} & \text{10 million}\\ \text{A0} & \text{9600} & \text{3.3} & \text{500 million}\\ \text{F0} & \text{7350} & \text{1.7} & \text{2.7 billion}\\ \text{G0} & \text{6050} & \text{1.1} & \text{9 billion}\\ \text{K0} & \text{5240} & \text{0.8} & \text{14 billion}\\ \text{M0} & \text{3750} & \text{0.4} & \text{200 billion}\\ \end{matrix}$$