What is an estimated number?

a.

An integer

c.

An exact number

b.

An imaginary number

d.

A measured numbe

Which of the following metals is the most reactive and why? copper sodium magnesium zinc

How do biologists learn which organisms we're the ancestors of today's plants?

Convert 145.0 mm to meters and express the answer to the correct number of significant digits.

The periodic table has undergone some changes since it was first introduced. List three ways the modern periodic table differs from the one first published by Mendeleev in 1869.

You have a block of dry ice (-40°C), an ice cube (-5°C) and alcohol (15°C). In which one do molecules move the fastest? A. Ice Cube B. Dry Ice C. Water D. Alcohol

The first-order decomposition of n2o at 1000 k has a rate constant of 0.76 s-1. if the initial concentration of n2o is 10.9 m, what is the concentration of n2o after 9.6 s

When a catalyst lowers the activation energy of a reaction the rate of the reaction?

Liquids: A) must be contained to stay in one spot B) have a variable volume, but a fixed mass C) are usually more dense than solids and gases D) cannot be changed into gases

Given the following list from the activity series of metals (from most active to least active) K, Na, Al, Mn, Cr, Cd, Co, Pb, Hg which reaction would you NOT expect to occur? 1. Co²⁺ (aq) + Al (s) → Al³⁺ (aq) + Co (s) 2.

Chemical reactions that release energy A. will not occur. B. need catalysts to occur. C. will always explode. D. often occur spontaneously.