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General Science

Which of the following substances gives up negatively charged hydroxide ions (OH^-) when dissolved in water?

base

An acid is a substance that gives up positively charged hydrogen ions (H⁺) when dissolved in water. A base (alkaline) gives up negatively charged hydroxide ions (OH^-) when dissolved in water. pH is a scale that measures of how basic or acidic a solution is. Numbered from 0 to 14, solutions with a pH of 7 are neutral, less than 7 are acidic, more than 7 are alkaline.

General Science

Which of the following describes the Earth's mantle?

primarily solid

Mantle makes up 84% of the Earth's volume and has an average thickness of approximately 1,800 miles (2,900 km). It is dense, hot, and primarily solid although in places it behaves more like a viscous fluid as the plates of the upper mantle and crust gradually "float" along its circumference.

Math Knowledge

Which of the following is not a part of PEMDAS, the acronym for math order of operations?

pairs

When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

General Science

Small rocks shed by asteroids and comets that reach the earth are called:

meteorites

Smaller rocks shed by asteroids and comets are called meteoroids. When these rocks reach Earth's atmosphere, they burn up in the mesosphere and become meteors. If a meteor manages to reach the Earth, it is called a meteorite.

Automotive Information

What provides the power necessary to start a car?

battery

The battery supplies the power necessary to start the engine when the ignition switch is is turned on.

Mechanical Comprehension

Connected gears of different numbers of teeth are used together to change which of the following charasteristics of the input force?

torque

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

Word Knowledge

Liability most nearly means:

handicap

A person or thing whose presence or behavior is likely to cause embarrassment or put one at a disadvantage.

Electronics Information

Which of the following can conduct electricity under some conditions but not others?

semiconductor

Semiconductors have valence shells that are exacly half full and can conduct electricity under some conditions but not others. This property makes them useful for the control of electrical current.

Shop Information

This tool is a(n) __________.

inside caliper

Calipers are similar to micrometers in shape but instead of measuring distances, calipers are used to transfer distances between objects. An outside caliper is used to transfer outside dimensions while an inside caliper is used to transfer inside distances. A vernier caliper is an extremely precise caliper (down to \({1 \over 1000}\) inch) that allows measuring / transferring either inside or outside dimensions.

Math Knowledge

This diagram represents two parallel lines with a transversal. If d° = 140, what is the value of x°?

140

For parallel lines with a transversal, the following relationships apply:

angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°)
alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°)
all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other
same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°)

Applying these relationships starting with d° = 140, the value of x° is 140.