Is it permissible to make ablution without answering the call of nature after waking up?
Washing front and back openings (Istinjaa`) is not a condition for the validity of ablution because it is done to remove Najaasah (impurity), thus if there is no Najaasah, there is no need for that, and then it is permissible to make ablution without answering the call of nature. However, prayer is invalidated if there is Najaasah on the anus ,or the front opening, so it (Najaasah) must be removed for the prayer to become valid, and not the ablution.
Should the Zakah (obligatory charity) giver tell the poor recipient that this is the Zakah of his money?
No, he shouldn`t. But, the Zakah giver should make an intention in his heart that it is the Zakah of his money when paying it to the poor. And Allah Knows Best.
What is the ruling of Islamic Law on colleagues alternating overtime shifts and receiving wages for absent days?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
An employee is religiously obligated to abide by the instructions and regulations pertaining to overtime hours. Furthermore, it is mandatory to adhere to honesty and avoid deceit, circumvention, and falsehood. Allah Almighty says (what means): "O you who have believed, be conscious of Allah and be with those who are truthful."
(At-Tawbah/119).
Therefore, whoever is assigned to work overtime must remain present at the designated workplace, even if no active tasks are required of them during that time.
Likewise, the official authorized to approve overtime work must comply with all established conditions and regulatory guidelines. It is impermissible for them to grant overtime hours in violation of system regulations. Should any compensation be disbursed in contravention of these official rules, it is unlawful to accept or consume such wages. And Allah Almighty knows best.
Is it permissible to offer prayer at home, or should it be offered in the mosque?
All perfect praise be to Allah, The Lord of The Worlds. It isn`t preferable for the man to pray at home as praying in the mosque is twenty seven times more rewarding. Therefore, this should motivate him to offer prayers in the mosque. And Allah Knows Best.