Ques: Q: To measure what changes that occur in chemical reactions, chemists usually use a related thermodynamic quantity, calledenthalpy? Read this paragraph and choose the correct option from the provided answers: (a) Initially, the system (a copper penny and concentrated nitric acid) is at atmospheric pressure. (b) When the penny is added to the nitric acid, the volume of NO2 gas that is formed causes the piston to move upward to maintain the system at atmospheric pressure. In doing so, the system is performing work on its surroundings. The symbol E in represents the internal energy of a system, which is the sum of the kinetic energy and potential energy of all its components. It is the change in internal energy that produces heat plus work. To measure the energy changes that occur in chemical reactions, chemists usually use a related thermodynamic quantity calledenthalpy (H) (from the Greek enthalpein, meaning "to warm"). The enthalpy of a system is defined as the sum of its internal energy E plus the product of its pressure Pand volume V:. Choices: - ion exchange - evaporation - entropy - energy A:
Ans: energy

Ques: Q: What planet is a blue green color? Read this paragraph and choose the correct option from the provided answers: Uranus is a lot like Jupiter and Saturn. The planet is composed mainly of hydrogen and helium. There is a thick layer of gas on the outside. Further on the inside is liquid. But Uranus has a higher percentage of icy materials than Jupiter and Saturn. These materials include water, ammonia, and methane. Uranus is also different because of its blue-green color. Clouds of methane filter out red light. This leaves a blue-green color. The atmosphere of Uranus has bands of clouds. These clouds are hard to see in normal light. The result is that the planet looks like a plain blue ball. Choices: - Mars - sirius - Mercury - uranus A:
Ans: uranus

Ques: Q: What is the measure of the change in the velocity of a moving object called? Read this paragraph and choose the correct option from the provided answers: A car's gas pedal, like the one in Figure below , is sometimes called the accelerator. That's because it controls the acceleration of the car. Pressing down on the gas pedal gives the car more gas and causes the car to speed up. Letting up on the gas pedal gives the car less gas and causes the car to slow down. Whenever an object speeds up, slows down, or changes direction, it accelerates. Acceleration is a measure of the change in velocity of a moving object. Acceleration occurs whenever an object is acted upon by an unbalanced force. Choices: - transmission - compression - pressurization - acceleration A:
Ans: acceleration

Ques: Q: At any specific time, the rate at which a reaction is proceeding is known as its what? Read this paragraph and choose the correct option from the provided answers: To obtain the tabulated results for this decomposition, the concentration of hydrogen peroxide was measured every 6 hours over the course of a day at a constant temperature of 40 C. Reaction rates were computed for each time interval by dividing the change in concentration by the corresponding time increment, as shown here for the first 6-hour period: [H 2 O 2] (0.500 mol/L 1.000 mol/L) = = 0.0833 mol L 1 h 1 t (6.00 h 0.00 h) Notice that the reaction rates vary with time, decreasing as the reaction proceeds. Results for the last 6-hour period yield a reaction rate of: [H 2 O 2] (0.0625 mol/L 0.125 mol/L) = = 0.0104 mol L 1 h 1 t (24.00 h 18.00 h) This behavior indicates the reaction continually slows with time. Using the concentrations at the beginning and end of a time period over which the reaction rate is changing results in the calculation of an average rate for the reaction over this time interval. At any specific time, the rate at which a reaction is proceeding is known as its instantaneous rate. The instantaneous rate of a reaction at "time zero," when the reaction commences, is its initial rate. Consider the analogy of a car slowing down as it approaches a stop sign. The vehicle's initial rateanalogous to the beginning of a chemical reactionwould be the speedometer reading at the moment the driver begins pressing the brakes (t0). A few moments later, the instantaneous rate at a specific momentcall it t1would be somewhat slower, as indicated by the speedometer reading at that point in time. As time passes, the instantaneous rate will continue to fall until it reaches zero, when the car (or reaction) stops. Unlike instantaneous speed, the car's average speed is not indicated by the speedometer; but it can be calculated as the ratio of the distance traveled to the time required to bring the vehicle to a complete stop (t). Like the decelerating car, the average rate of a chemical reaction will fall somewhere between its initial and final rates. The instantaneous rate of a... Choices: - spontaneous rate - immediate rate - emitted rate - instantaneous rate A:
Ans:
instantaneous rate