A teacher performs a demonstration to show the properties of an unknown substance. The teacher cuts off a piece of gray shiny substance and drops it in water. The substance floats and reacts violently with the water. Based on this Information, what type of element the unknown substance? A. metalloid
B. metal
C. nonmental
D. halogen​

An ideal spring has a spring constant (force constant) of 2500 n/m, is stretched 4.0 cm, how much elastic potential energy does it possess? (a) 3j (b) 0.00j (c) 1j (d) 2j (e) 4j

An object's buoyant force and weight mean the same thing.a. trueb. false

Two resistors r1 and r2 may be connected either in series or parallel across an ideal battery with emf ε. we desire the rate of energy dissipation of the parallel combination to be 8.75 times that of the series combination. if r1 = 105 ω, what are the (a) smaller and (b) larger of the two values of r2 that result in that dissipation rate?