<span>The element gold has 32 isotopes, ranging from A =173 to A = 204. during alpha decay Au will loose 2 in atomic number and 4 in mass number . it will form a iridium isotope and helium . according to the above statement, the balanced equation for the alpha decay of gold 173 will be given as below.
173 169 4
79 Au-------------->77 Ir + 2He</span>
The problem talks about two questions and these are:
1. Metals are very good conductors of electricity and heat. Directing heat is easier. So let Marie heat the beads and also have heat another substance, for instance, water. If the beads heat quicker, then they are metals. Another test to conduct is called flame test. This test should give you a colored flame (blue/white for lead) the metal is lead if the reaction is: 2PbO+C ==> 2Pb +CO2
2. The beads are possibly to be lead since Ferrous(lead) oxide + carbon = carbon dioxide + lead
Answer = c
Conservation of mass (mass is never lost or gained in chemical reactions), during chemical reaction no particles are created or destroyed, the atoms are rearranged from the reactants to the products.
Answer : The correct option is, 
Explanation :
Formula used :
where,
= heat released = 24 KJ
= mass of bomb calorimeter = 1.30 Kg
= specific heat = 
= final temperature = ?
= initial temperature = 
Now put all the given values in the above formula, we get the final temperature of the calorimeter.
Therefore, the final temperature of the calorimeter is,
The warmer road surface at the end of a sunny day is the black road because during the day it absorbed more radiation (sunlight) than the withe one
