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Questions in Grade Middle-school

📝 Answered - An electron in a sodium atom gains enough energy to move from the second shell to the third shell. The sodium atom becomes: 1. a positive ion 2. a negative ion 3. an atom in an excited state 4. an atom in the ground state

📝 Answered - Two times Antonio’s age plus three times Sarah’s age equals 34. Sarah’s age is also five times Antonio’s age. How old is Sarah?

📝 Answered - Which quantity represents the number of protons in an atom? (a) atomic number (b) oxidation number (c) number of neutrons (d) number of valence electrons

📝 Answered - The elements in Group 2 have similar chemical properties because each atom of these elements has the same: (a) atomic number (b) mass number (c) number of electron shells (d) number of valence electrons

📝 Answered - Why are some constellations visible to New York State observers at midnight during April, but not visible at midnight during October? (a) Constellations move within our galaxy. (b) Constellations have elliptical orbits. (c) Earth revolves around the Sun. (d) Earth rotates on its axis.

📝 Answered - A dry-bulb temperature of 30°C and a wet-bulb temperature of 29°C were recorded at a weather station. What are the relative humidity and the most likely weather conditions? 1. Relative humidity is 29% with clear skies. 2. Relative humidity is 29% with a good chance of snow. 3. Relative humidity is 93% with clear skies. 4. Relative humidity is 93% with a good chance of rain. How do you determine the correct answer?

📝 Answered - Jerome surveyed 643 skateboarders and found that 209 of them preferred wood skateboards to plastic or aluminum skateboards. Based on the number of people surveyed, what is the most reasonable estimation of the percent of skateboarders who preferred wood skateboards? A. 10% B. 30% C. 40% D. 50%

📝 Answered - Solve the equation below for \( x \): \[ 9(x - 5) = 4x - 5 \]

📝 Answered - If \( P = a^2 + a - 1 \) and \( R = -a - 1 \), which expression represents \( P + R \)? a) \( a^2 + 2 \) b) \( a^2 - 2 \) c) \( a^2 + 2a \) d) \( a^2 + 2a - 2 \)

📝 Answered - After decaying for 48 hours, 1/16 of the original mass of a radioisotope sample remains unchanged. What is the half-life of this radioisotope?