Earth is approximately four.5 billion years old is it likely that any of the rock there on earth surface when it when it first formed are still in existence

In the circuit shown below, with each bulb holding a resistance of 60 ohms, how many amps of current are flowing? express your number as a decimal.

Which of the following are guidelines to follow for obtaining accurate observations

An architect plans to use solar energy to heat the next house he designs. what principle of absorption and infrared energy can be applied to the design of the new house? how could she apply to those principals?