How do the number of valence electrons an element has change from column to column?

A student is heating a chemical in a beaker with a Bunsen burner. In a paragraph of at least 150 words, identify the safety equipment that should be used and the purpose of it for the given scenario. What do i put

The hormones released due to stress lead to increased risk of pregnancy.

How does the mass and height of an object affect the gravitational potential energy?

Use the information in the square to answer the questions about copper. how many protons are in an atom of copper? how many electrons are in an atom of copper? how many neutrons are in an atom of copper? round your answer to the nearest whole number.

Will it give me the right answers

1 75 ml of lemon juice are added to 50 ml of water. What is the percent by vo of the solute?

How many moles of tungsten atoms are in 4.8 x 1025 atoms of tungsten?

At what speeds do you criuse down the track of a roller coaster

A sample of hydrogen gas is mixed with water vapor. The mixture has a total pressure of 755 torr and the water vapor has a partial pressure of 24 torr. What amount (in moles) of hydrogen gas is contained in 1.55 L of this mixture at 298 K?

Both equation I and II are balanced, but equation II is the correct way to write the balanced equation. Why do you think this is? (Hint: Think fractions.) I) 2 SnO2 + 4 H2 → 2 Sn + 4 H2O II) SnO2 + 2 H2 → Sn + 2 H2O