Please help me and get 15 points and Brainlessly Bauxite is the chief ore from which aluminum is extracted. Which of these statements is correct about bauxite? (15 points)
Group of answer choices

It has a definite crystal structure.

It does not have a definite chemical composition.

Its atoms do not arrange themselves in a definite order.

Its molecules are made up of a different number of atoms.

Let f(x) = x4- 8x2 . find the relativeextrema of this function using the second derivative test.

Aparticle travels in a circular orbit of radius 21 m. its speed is changing at a rate of 23.1 m/s2 at an instant when its speed is 37.2 m/s. what is the magnitude of the acceleration (in m/s? ) of the particle?

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?