You want to divide by avagadros number (6.22 x 10^23). This will cancel the atoms unit and give moles, moles of Iridium. Now you want to calculate the atomic mass of Iridium which is in units of grams per mole. Multiply these two numbers and the moles will cancel giving you grams.
Setting up a dimension analysis type of thing helps tremendously. See what you have to cancel in order to get what you want. We canceled the atoms, then we canceled the moles, and then we got grams.
Answer:
false, Potassium and fluorine are not halogens.
only fluorine here is halogen.
potassium is an alkali earth metal it doesn't comes under category of halogens, but fluorine
is a non metal which comes under halogen family.
1) when litmus paper is dipped into a acid solution, the litmus paper turns red.
<span>2) acid reacts with metals to produce hydrogen gas </span>
<span>3) the equation of an acidic substance begins with the letter 'H' such as HCl </span>

The reaction creates dihydrogen, hence if it's uncontrolled it could lead to potentially dangerous amounts of gas being released at once.